Data transmission method

ABSTRACT

Encrypted auxiliary information data DYAE/DCAE including no inhibited codes is generated based on auxiliary information data DYA/DCA including no inhibited codes, in an auxiliary data packet having an auxiliary data flag ADF formed of a first combination of a plurality of inhibited codes, the auxiliary data flag ADF is replaced with an auxiliary data flag EADF formed of a second combination of the inhibited codes, the second combination being different from the first combination, to form an encrypted auxiliary data packet having the auxiliary data flag EADF and including the encrypted auxiliary information data DYAE/DCAE, and the encrypted auxiliary data packet is transmitted.

TECHNICAL FIELD

The present invention described in the claims of this applicationrelates to a data transmission method of encrypting digital informationdata forming a data packet and transmitting the encrypted data and adata transmission apparatus implementing the data transmission method,and to a data reception method of receiving the transmitted encrypteddata and decrypting the encrypted data to reproduce the original dataand a data reception apparatus implementing the data reception method.

BACKGROUND ART

In transmission of digital data representing a variety of signalinformation etc., encrypting the digital data to be transmitted at atransmission side and decrypting the encrypted digital data to reproducethe original data at a reception side are proposed in order to prevent,for example, tapping in the data transmission path. Known and typicalencryption algorithms adopted in the encryption of digital data includea data encryption standard (DES) method published by the National Bureauof Standards (NBS) in the US Department of Commerce in 1977 and anadvanced encryption standard (AES) method published by the NationalInstitute of Standards and Technology (NIST) under the jurisdiction ofthe US Department of Commerce in 2001 (for example, refer to “ADVANCEDENCRYPTION STANDARD (AES) (FIPS PUB 197)”, Nov. 26, 2001, Department ofCommerce, National Institute of Standards and Technology, InformationTechnology Laboratory).

Basically, in the encrypted transmission by the DES method or the AESmethod, digital data to be transmitted is encrypted in accordance with arule defined in key data (encryption key data) separately provided andthe encrypted digital data is decrypted in accordance with a ruledefined in key data (decryption key data) separately provided. Key data(common key data) is used as the encryption key data and the decryptionkey data. The algorithms for the encryption and the decryption aredisclosed, and the common key data is kept secret to ensureconfidentiality.

In the field of video signals, digitization is encouraged in order torealize diversification of transmitted information and increase inquality of reproduced images. For example, high definition television(HDTV) systems that process digital video signals formed of digital datarepresenting information concerning the video signals have beenproposed. Digital video signals (hereinafter referred to as HD signals)in the HDTV systems are formed in accordance with, for example, the BTAS-002 standard established by the Broadcasting Technology Association(BTA) (refer to “BTA S-002 1125/60 Kouseido terebijon houshiki sutajiodhizitaru eizo kikaku”, February 1992, BTA) and have a Y-P_(B)/P_(R)format and a G-B-R format. In the Y-P_(B)/P_(R) format, Y means aluminance signal and P_(B)/P_(R) means a color difference signal. In theG-B-R format, G means a green primary color signal, B means a blueprimary color signal, and R means a red primary color signal.

For example, each frame period in each of the HD signals is divided intoa first field period and a second field period. The HD signal has aframe rate of 30 Hz (a field rate of 60 Hz), has 1,125 lines for everyframe period, has 2,200 data samples for every line, and has a samplingfrequency of 74.25 MHz. The HD signal in the Y-P_(B)/P_(R) formatcomplies with a data format shown in FIG. 1.

In the data format in FIG. 1, reference letter A in FIG. 1 indicatespart of one line in a luminance-signal data sequence (Y data sequence)representing a luminance signal component in the video signal, andreference letter B in FIG. 1 indicates part of one line in acolor-difference-signal data sequence (P_(B)/P_(R) data sequence)representing a color difference signal component in the video signal.Each word data forming the Y data sequence and the P_(B)/P_(R) datasequence includes, for example, 10 bits. In other words, each of the Ydata sequence and the P_(B)/P_(R) data sequence is 10-bit word sequencedata having continuous 10-bit words and has a word transmission rate of,for example, 74.25 Mwps.

Each line of the Y data sequence has a line blanking area and video datacontinuously formed therein. In the Y data sequence, timing referencecode data (SAV: Start of Active Video) including four words (3FF(Y),000(Y), 000(Y), and XYZ(Y); since “3FF” and “000” are hexadecimalnumbers, “h” indicating the hexadecimal number is added to “3FF” and“000”, which are represented as “3FFh” and “000h”, and (Y) indicates aword in the Y data sequence), each word including 10 bits, is arrangedimmediately before the video data. Timing reference code data (EAV: Endof Active Video) including four words (3FF(Y), 000(Y), 000(Y), andXYZ(Y)), each word including 10 bits, is arranged immediately after thevideo data. Also in the P_(B)/P_(R) data sequence, SAV including fourwords (3FF(C), 000(C), 000(C), and XYZ(C); (C) indicates a word in theP_(B)/P_(R) data sequence), each word including 10 bits, is arrangedimmediately before the video data, and EAV including four words (3FF(C),000(C), 000(C), and XYZ(C)), each word including 10 bits, is arrangedimmediately after the video data. The EAV and SAV in the Y data sequenceare arranged in the line blanking area in the Y data sequence, and theEAV and SAV in the P_(B)/P_(R) data sequence are arranged in the lineblanking area in the P_(B)/P_(R) data sequence.

Among the four words (3FF(Y), 000(Y), 000(Y), and XYZ(Y) or 3FF(C),000(C), 000(C), and XYZ(C)), the first three words ((3FF(Y), 000(Y), and000(Y) or 3FF(C), 000(C), and 000(C)) are provided for establishing wordsynchronization or line synchronization, and the last one word (XYZ(Y)or XYZ(C)) is provided for discriminating between the first field andthe second field in the same frame or for discriminating between thetiming reference code data EAV and the timing reference code data SAV.

In the HD signal including the Y data sequence and the P_(B)/P_(R) datasequence, multiple codes that includes timing identification codesforming the timing reference codes data SAV and EAV and that are notused as information codes forming the video data are defined for the Ydata sequence and the P_(B)/P_(R) data sequence as inhibited codes. Theinhibited codes are equal to 000h to 003h and 3FCh to 3FFh (hexadecimalnumbers), that is, 0000000000 to 0000000011 and 1111111100 to 1111111111when the Y data sequence and the P_(B)/P_(R) data sequence are 10-bitword sequence data.

Auxiliary data used for transmitting information different from thedigital video signal represented by the video data is arranged in theline blanking area in the Y data sequence and the P_(B)/P_(R) datasequence, in addition to line number data and error detection code data.The auxiliary data is standardized in accordance with the BTA S-005Bstandard (refer to “BTA S-005B 1125/60 houshiki HDTV bitto chokuretsuintafeisu ni okeru hojo deta no kyoutsuu kikaku”, March 1998, ARIB)established by the Association of Radio Industries and Business (ARIB).

The standardized auxiliary data forms a data packet including apredetermined number (one or more) of words. A first format shown byreference letter A in FIG. 2 and a second format shown by referenceletter B in FIG. 2 are set for the data packet formed of the auxiliarydata (auxiliary data packet).

The auxiliary data packet in the first format (shown by referencenumeral A in FIG. 2) includes 7 to 262 words (each word includes 10bits). In the auxiliary data packet in the first format, a three-wordauxiliary data flag (ADF), a one-word data identification word (DID), aone-word data block number word (DBN), a one-word data count word (DC),a user data word (UDW) of 0 to 255 words, and a one-word checksum word(CS) are sequentially arranged. The auxiliary data packet in the secondformat (shown by reference letter B in FIG. 2) differs from theauxiliary data packet in the first format in that a one-word second dataidentification word (SDID) is used instead of the one-word data blocknumber word (DBN) but is similar to the auxiliary data packet in thefirst format in other aspects.

The ADF denotes the start of the auxiliary data packet and hascontinuous three words arranged therein, which are a combination of000h, 3FFh, and 3FFh and to which the inhibited codes described aboveare set. The DID denotes a type of the UDW. Eight bits among the 10 bitsare used for information and the higher two bits are used for avoidingthe inhibited codes. The DBN denotes the order of the auxiliary datapackets having the same DID. Eight bits among the 10 bits are used forinformation and the higher two bits are used for avoiding the inhibitedcodes. The DC denotes the number (0 to 255) of words in the UDW. Eightbits among the 10 bits are used for information and the higher two bitsare used for avoiding the inhibited codes.

The UDW is 10-bit data which includes no inhibited code and to which acode within a range from 004h to 3FBh is set, and is information datarepresenting information to be transmitted in the auxiliary data. The CSdenotes a checksum value. Nine bits among the 10 bits are used forinformation and the highest one bit is used for avoiding the inhibitedcodes. The SDID denotes a type of the UDW, like the DID. Eight bitsamong the 10 bits are used for information and the higher two bits areused for avoiding the inhibited codes.

When the auxiliary data is used for transmitting digital audioinformation (digital audio auxiliary data), the digital audio auxiliarydata is standardized, separately from the general auxiliary data, inaccordance with the BTA S-006B standard (“BTA S-006B 1125/60 houshikiHDTV bitto chokuretsu intafeisu ni okeru dhizitaru onsei kikaku”, March1998, ARIB) established by the ARIB described above.

The standardized digital audio auxiliary data also forms a data packethaving a predetermined number (one or more) of words. The data packetformed of the digital audio auxiliary data (audio data packet) has thefirst format shown by reference letter A in FIG. 2, as shown in FIG. 3.

The audio data packet (FIG. 3) includes 31 words (each word includes 10bits). In the audio data packet, a three-word ADF, a one-word DID, aone-word DBN, a one-word DC, a 24-word UDW, and a one-word CS aresequentially arranged.

In the audio data packet, the ADF denotes the start of the audio datapacket and has continuous three words arranged therein, which are acombination of 000h, 3FFh, and 3FFh and to which the inhibited codesdescribed above are set. The DID indicates that the content of the UDWis digital audio information. Eight bits among the 10 bits are used forinformation and the higher two bits are used for avoiding the inhibitedcodes. Specifically, for example, the DID set to a code 2E7h indicatesinformation belonging to an audio group 1 on channels 1 to 4, the DIDset to a code 1E6h indicates information belonging to an audio group 2on channels 5 to 8, the DID set to a code 1E5h indicates informationbelonging to an audio group 3 on channels 9 to 12, and the DID set to acode 2E4h indicates information belonging to an audio group 4 onchannels 13 to 16. The DBN, DC, and the CS are similar to those in theauxiliary data packet described above.

The UDW is digital audio information data representing digital audioinformation to be transmitted in the digital audio auxiliary data. Ineach word in the digital audio information data, the remaining eightbits, excluding the higher two bits among the 10 bits, normally serve asinformation bits. In each of the 24 words in the UDW, eight bits amongthe 10 bits are used for information and the higher two bits are usedfor avoiding the inhibited codes. In the 24 words, the first two words(UDW0 and UDW1) represent audio clock phase information, the 16 wordsfrom the third word to the eighteenth word (UDW2 to UDW 17) representdigital audio data, and the six words from the nineteenth word to thelast word (UDW18 to UDW23) represent error correction data.

When the HD signal including the Y data sequence or the HD signalincluding the P_(B)/P_(R) data sequence, described above, istransmitted, it is desirable to realize serial transmission in which theword sequence data is converted into serial data for transmissionbecause the data transmission path is simplified in the serialtransmission. The serial transmission of the HD signals including the Ydata sequence and the P_(B)/P_(R) data sequence is standardized so as toperform transmission in compliant with a high definition-serial digitalinterface (HD-SDI) in the BTA S-004 standard (refer to “BTA S-0041125/60 houshiki HDTV shingou no bitto chokuretsu intafeisu kikaku”,April 1995, BTA) established by the BTA described above.

In the transmission compliant with the HD-SDI, word multiplexing isperformed for the Y data sequence and the P_(B)/P_(R) data sequence insynchronization with the line blanking area having the EAV and the SAVarranged therein to form a word multiplexed data sequence shown in FIG.4 as 10-bit word sequence data having a word transmission rate of 74.25Mwps×2=148.5 Mwps. In the word multiplexed data sequence, multiplexedtiming reference code data (multiplexed SAV) including eight words(3FF(C), 3FF(Y), 000(C), 000(Y), 000(C), 000(Y), XYZ(C), and XYZ(Y)),each word including 10 bits, is arranged immediately before the videodata, and multiplexed timing reference code data (multiplexed EAV)including eight words (3FF(C), 3FF(Y), 000(C), 000(Y), 000(C), 000(Y),XYZ(C), and XYZ(Y)), each word including 10 bits, is arrangedimmediately after the video data.

The bits, from the least significant bit (LSB) to the most significantbit (MSB), in each of the 10-bit words in the word multiplexed datasequence are sequentially transmitted to convert the parallel data tothe serial data, scrambling is performed for the serial data to generatea serial transmission HD signal (hereinafter referred to as an HD-SDIsignal), and the HD-SDI signal is transmitted through the datatransmission path. The HD-SDI signal has a bit transmission rate of, forexample, 148.5 Mwps×10 bits=1.485 Gbps.

In the transmission of the HD-SDI signal through the data transmissionpath, described above, there are cases in which it is desirable that theHD-SDI signal be encrypted at the transmission side and the encryptedHD-SDI signal be decrypted to reproduce the original HD-SDI signal atthe reception side in order to prevent, for example, tapping on the datatransmission path to improve the security of the informationtransmission. In principle, the encrypted transmission of the HD-SDIsignal can also be performed in the encrypted transmission systemadopting the DES method or the AES method described above.

Encrypting the video data in the HD signal that forms the HD-SDI signaland that includes the Y data sequence and the P_(B)/P_(R) data sequenceto generate encrypted video data, which include no inhibited code,forming an encrypted HD signal including the encrypted video data,performing parallel-serial (P/S) conversion for the encrypted HD signalto generate an encrypted HD-SDI signal, and transmitting the encryptedHD-SDI signal through the data transmission path have already beenproposed by the applicant of this application in the patent applicationNo. 2002-135039 filed in May 10, 2002.

Although the transmission of the HD-SDI signal including the video datasubjected to the encryption through the data transmission path hasalready been proposed, it is desirable that auxiliary data, for example,the digital audio auxiliary data, included in the HD signal forming theHD-SDI signal be encrypted in order to further improve the security inthe information transmission. Specifically, it is desirable to form anencrypted HD signal including encrypted auxiliary data, to perform theP/S conversion for the encrypted HD signal to generate an encryptedHD-SDI signal, and to transmit the encrypted HD-SDI signal through thedata transmission path.

Accordingly, in the transmission of the HD-SDI signal, encrypting theUDW in the auxiliary data packet formed of the auxiliary data includedin the HD signal forming the HD-SDI signal, as in the video data, togenerate an encrypted UDW, forming an encrypted auxiliary data packetincluding the encrypted UDW, generating an encrypted HD signal includingthe encrypted auxiliary data packet, and transmitting an encryptedHD-SDI signal based on the encrypted HD signal are suggested.

However, the generation of the encrypted HD signal including theencrypted auxiliary data packet and the transmission of the encryptedHD-SDI signal based on the encrypted HD signal by using technologiesalready proposed have the following disadvantages.

First, problems can be caused at the reception side receiving theencrypted HD-SDI signal to generate the encrypted auxiliary data packet.Although such problems are not caused when the receiving apparatusreceiving the encrypted HD-SDI signal to generate the encryptedauxiliary data packet from the encrypted HD-SDI signal includesdecryption means for decrypting the encrypted UDW included in theencrypted auxiliary data packet to reproduce the original UDW, theproblems are caused when the receiving apparatus does not include thedecryption means, for example, when known receiving apparatuses areused.

For example, when the encrypted auxiliary data packet is an encryptedaudio data packet including the UDW having encrypted digital audioinformation, a-receiving apparatus generating the encrypted audio datapacket from the encrypted HD-SDI signal detects an ADF included in theencrypted audio data packet to recognize the start of the encryptedaudio data packet, extracts the encrypted UDW from the encrypted audiodata packet, and supplies the encrypted UDW to an audio reproducingunit. When the receiving apparatus includes the decryption means in theaudio reproducing unit, the decryption means in the audio reproducingunit performs the decryption for the encrypted UDW to generate a UDWhaving the original digital audio information, an appropriate reproducedaudio signal based on the generated UDW is generated, and the reproducedaudio signal is supplied to audio reproducing means, for example, aspeaker. As a result, an appropriate reproduced sound based on theappropriate reproduced audio signal is output from the speaker. Incontrast, when the receiving apparatus does not include the decryptionmeans in the audio reproducing unit, an undesired audio signal based onthe encrypted UDW is generated because the decryption is not performedfor the encrypted UDW in the audio reproducing unit, and the undesiredaudio signal is supplied to the audio reproducing means, for example,the speaker. As a result, for example, an excessive current based on theundesired audio signal is possibly applied to the speaker to damage thespeaker.

Next, for example, when the encrypted auxiliary data packet is anencrypted audio data packet including the UDW having encrypted digitalaudio information, the encryption possibly causes a reduction inperformance of the error correction of the encrypted UDW based on theUDW including an error correction code.

Furthermore, for example, a stream converter using a first-in first-out(FIFO) memory can be used for the encryption in the generation of theencrypted auxiliary data packet. In such a case, since some lines in theY data sequence and the P_(B)/P_(R) data sequence forming the HD signalare largely occupied by the auxiliary data, the writing period for theFIFO memory is not sufficiently provided to cause a state in which theFIFO memory is emptied. As a result, a reduction in quality of theencryption security of the encrypted auxiliary data packet is probablycaused.

In the generation of the encrypted HD signal including the encryptedauxiliary data packet and the transmission of the encrypted HD-SDIsignal based on the encrypted HD signal, having the above disadvantages,it is desirable that the encryption be selectively performed for everyauxiliary data packet in each line in the Y data sequence and theP_(B)/P_(R) data sequence forming the HD signal in order to improve theflexibility in the actual use.

The present invention described in the claims of this applicationprovides a data transmission method capable of generating the encryptedauxiliary data packet by the encryption of the auxiliary data packetformed of the auxiliary data included in a signal, such as the HDsignal, forming the HD-SDI signal, capable of generating the encryptedsignal, such as the encrypted HD signal, including the encryptedauxiliary data packet, and capable of transmitting the serial signal,such as the encrypted HD-SDI signal, based on the encrypted signal suchthat the disadvantages involved in the application of the above knowntechnologies that have been proposed can be avoided and the encryptioncan be selectively performed for every auxiliary data packet, andprovides a data transmission apparatus implementing the datatransmission method. In addition, the present invention provides a datareception method capable of receiving the serial signal, such as theencrypted HD-SDI signal, formed and transmitted based on the encryptedsignal, such as the encrypted HD signal, including the encryptedauxiliary data packet, the encrypted auxiliary data packet beinggenerated by the encryption of the auxiliary data packet formed of theauxiliary data included in a signal, such as the HD signal, forming theHD-SDI signal, capable of generating the encrypted signal, such as theencrypted HD signal, and the encrypted auxiliary data packet from theserial signal, such as the encrypted HD-SDI signal, and capable ofperforming the decryption for the generated encrypted auxiliary datapacket to reproduce the auxiliary data forming the original auxiliarydata packet, and provides a data reception apparatus implementing thedata reception method.

DISCLOSURE OF INVENTION

A data transmission method according to the invention described in anyof Claims 1 to 3 in the claims of this application includes the steps ofperforming encryption for information data included in a data packethaving a data flag formed of a first combination of a plurality ofinhibited codes that are not used as information codes representinginformation, the information data being formed without using theinhibited codes, so as not to generate the inhibited codes in order togenerate encrypted information data that includes no inhibited codes;replacing the first combination of the plurality of inhibited codes inthe data flag in the data packet with a second combination of theinhibited codes, the second combination being different from the firstcombination, to form an encrypted data packet that has the replaced dataflag and that includes the encrypted information data; and transmittingthe encrypted data packet.

A data transmission method according to the invention described in anyof Claims 4 to 6 in the claims of this application includes the steps ofperforming encryption for information data included in a data packethaving a data flag formed of a predetermined combination of a pluralityof inhibited codes that are not used as information codes representinginformation, the information data being formed without using theinhibited codes, the data flag being followed by identification datathat includes a first code other than the inhibited codes to represent atype of the information data, so as not to generate the inhibited codesin order to generate encrypted information data that includes noinhibited codes; replacing the first code included in the identificationdata in the data packet with a second code that is different from thefirst code and that is other than the inhibited codes to form anencrypted data packet that has the data flag followed by the replacedidentification data and that includes the encrypted information data;and transmitting the encrypted data packet.

A data transmission apparatus according to the invention described inany of Claims 7 to 9 in the claims of this application includes anencryption processing unit configured to perform encryption forinformation data included in a data packet having a data flag formed ofa first combination of a plurality of inhibited codes that are not usedas information codes representing information, the information databeing formed without using the inhibited codes, so as not to generatethe inhibited codes in order to generate encrypted information data thatincludes no inhibited codes; an encrypted-data-packet forming unitconfigured to replace the first combination of the plurality ofinhibited codes in the data flag in the data packet with a secondcombination of the inhibited codes, the second combination beingdifferent from the first combination, to form an encrypted data packetthat has the replaced data flag and that includes the encryptedinformation data generated by the encryption processing unit; and a datatransmitting unit configured to transmit the encrypted data packetformed by the encrypted-data-packet forming unit.

A data transmission apparatus according to the invention described inany of Claims 10 to 12 in the claims of this application includes anencryption processing unit configured to perform encryption forinformation data included in a data packet having a data flag formed ofa predetermined combination of a plurality of inhibited codes that arenot used as information codes representing information, the informationdata being formed without using the reserved codes, the data flag beingfollowed by identification data that includes a first code other thanthe reserved codes to represent a type of the information data, so asnot to generate the inhibited codes in order to generate encryptedinformation data that does not use the inhibited codes; anencrypted-data-packet forming unit configured to replace the first codeincluded in the identification data in the data packet with a secondcode that is different from the first code and that is other than thereserved codes to form an encrypted data packet that has the data flagfollowed by the replaced identification data and that includes theencrypted information data generated by the encryption processing unit;and a data transmitting unit configured to transmit the encrypted datapacket formed by the encrypted-data-packet forming unit.

A data reception method according to the invention described in any ofClaims 13 to 15 in the claims of this application includes the steps ofreceiving encrypted data packet that is transmitted and that has a dataflag formed of a second combination of a plurality of inhibited codesthat are not used as information codes representing information, withwhich second combination of the inhibited codes a first combination ofthe inhibited codes is replaced, the second combination being differentfrom the first combination, the encrypted data packet includingencrypted information data that includes no reserved codes and thatresults from encryption performed for information data formed withoutusing the inhibited codes so as not to generate the inhibited codes;performing decryption for the encrypted information data included in theencrypted data packet to generate reproduced information data; detectingthe data flag included in the encrypted data packet; and extracting thereproduced information data in accordance with a detection outputresulting from the detection.

A data reception method according to the invention described in any ofClaims 16 to 18 in the claims of this application includes the steps ofreceiving encrypted data packet that is transmitted, that has a dataflag formed of a predetermined combination of a plurality of inhibitedcodes that are not used as information codes representing information,and that includes encrypted information data resulting from encryptionperformed for information data formed without using the inhibited codesso as not to generate the inhibited codes and including no reservedcodes, the data flag being followed by identification data that has asecond code other than the inhibited codes, with which second code afirst code that is other than the inhibited codes and that represents atype of the information data is replaced, the second code beingdifferent from the first code; performing decryption for the encryptedinformation data included in the encrypted data packet to generatereproduced information data; detecting the identification data includedin the encrypted data packet; and extracting the reproduced informationdata in accordance with a detection output resulting from the detection.

A data reception apparatus according to the invention described in anyof Claims 19 to 21 in the claims of this application includes adata-sequence reproducing unit configured to receive encrypted datapacket that is transmitted and that has a data flag formed of a secondcombination of a plurality of inhibited codes that are not used asinformation codes representing information, with which secondcombination of the inhibited codes a first combination of the inhibitedcodes is replaced, the second combination being different from the firstcombination, the encrypted data packet including encrypted informationdata that includes no inhibited codes and that results from encryptionperformed for information data formed without using the inhibited codesso as not to generate the inhibited codes; a decryption processing unitconfigured to perform decryption for the encrypted information dataincluded in the encrypted data packet received by the data-sequencereproducing unit to generate reproduced information data; a datadetecting unit configured to detect the data flag included in theencrypted data packet; and a data selecting unit configured to extractthe reproduced information data generated by the decryption processingunit in accordance with a detection output supplied from the datadetecting unit.

A data reception apparatus according to the invention described in anyof Claims 22 to 24 in the claims of this application includes adata-sequence reproducing unit configured to receive encrypted datapacket that is transmitted, that has a data flag formed of apredetermined combination of a plurality of inhibited codes that are notused as information codes representing information, and that includesencrypted information data resulting from encryption performed forinformation data formed without using the inhibited codes so as not togenerate the inhibited codes and including no inhibited codes, the dataflag being followed by identification data that has a second code otherthan the inhibited codes, with which second code a first code that isother than the inhibited codes and that represents a type of theinformation data is replaced, the second code being different from thefirst code; a decryption processing unit configured to performdecryption for the encrypted information data included in the encrypteddata packet received by the data-sequence reproducing unit to generatereproduced information data; a data detecting unit configured to detectthe identification data included in the encrypted data packet; and adata selecting unit configured to extract the reproduced informationdata generated by the decryption processing unit in accordance with adetection output supplied from the data detecting unit.

In the data transmission method according to the invention described inany of Claims 1 to 3 in the claims of this application or the datatransmission apparatus according to the invention described in any ofClaims 7 to 9 in the claims of this application, the encryption isperformed for the information data included in the data packet havingthe data flag so as not to generate the inhibited codes to generate theencrypted information data including no inhibited codes; the firstcombination of the plurality of inhibited codes in the data flag isreplaced with the second combination of the inhibited codes, the secondcombination being different from the first combination, to form theencrypted data packet that has the replaced data flag and that includesthe encrypted information data; and the encrypted data packet istransmitted.

The encrypted information data including no inhibited codes is generatedand the encrypted data packet including the encrypted information datais transmitted in the above manner. Accordingly, in the generation ofencrypted serial data based on the transmitted encrypted data packet,the encrypted serial data does not include a part in which undesiredinhibited codes are converted into serial data.

The first combination of the plurality of inhibited codes forming thedata flag included in the encrypted data packet is replaced with thesecond combination of the inhibited codes, different from the firstcombination. Accordingly, when the receiving apparatus receiving thetransmitted encrypted data packet does not include decrypting means forthe encrypted information data included in the encrypted data packet,the data flag is not detected and, therefore, the encrypted data packetis not received, so that reproduction of information data based on theencrypted information data included in the encrypted data packet is notperformed. Consequently, for example, when the encrypted data packet isan encrypted audio data packet including encrypted digital audioinformation data having encrypted digital audio information and thereceiving apparatus receiving the encrypted data packet has a speaker,serving as audio reproducing means for reproducing audio based on thereproduced digital audio information, but does not have the decryptingmeans for the encrypted information data included in the encrypted datapacket, an undesirable audio signal formed based on the encryptedinformation data is not supplied to the speaker. As a result, asituation in which an excessive current based on the undesired audiosignal is applied to the speaker to damage the speaker can be avoided.

In the data transmission method according to the invention described inClaim 2 or the data transmission apparatus according to the inventiondescribed in Claim 8, the error correction data for the encryptedinformation data is generated along with the encrypted information dataand the encrypted information data and the error correction datacorresponding to the encrypted information data are included in theencrypted data packet. Accordingly, a situation in which the encryptioncauses a reduction in performance of the error correction of theencrypted information data can be avoided.

In the data transmission method according to the invention described inClaim 3 or the data transmission apparatus according to the inventiondescribed in Claim 9, the data packet is included in each of the datasequences and the encrypted data packet based on the data packet isformed for every data sequence. Accordingly, even when a streamconverter using an FIFO memory is used in the encryption in order toform an encrypted auxiliary data packet, a situation in which thewriting period for the FIFO memory is not sufficiently provided to emptythe FIFO memory does not arise. Consequently, a reduction in quality ofthe encryption security of the encrypted auxiliary data packet is notcaused.

With the data transmission method according to the invention describedin any of Claims 1 to 3 in the claims of this application or the datatransmission apparatus according to the invention described in any ofClaims 7 to 9 in the claims of this application, when the encrypted HDsignal including the encrypted auxiliary data packet is formed and theencrypted HD-SDI signal based on the encrypted HD signal is transmitted,it is possible to selectively perform the encryption for every auxiliarydata packet in each line of the Y data sequence and the P_(B)/P_(R) datasequence forming the HD signal, thus improving the flexibility in theactual use.

In the data transmission method according to the invention described inany of Claims 4 to 6 in the claims of this application or the datatransmission apparatus according to the invention described in any ofClaims 10 to 12 in the claims of this application, the encryption isperformed for the information data included in the data packet havingthe data flag followed by the identification data so as not to generatethe inhibited codes to generate encrypted information data that includesno inhibited codes; the first code in the identification data in thedata packet is replaced with the second code that is different from thefirst code and that is other than the inhibited codes to form theencrypted data packet that has the data flag followed by the replacedidentification data and that includes the encrypted information data;and the encrypted data packet is transmitted.

The encrypted information data including no inhibited codes is generatedand the encrypted data packet including the encrypted information datais transmitted in the above manner. Accordingly, in the generation ofencrypted serial data based on the transmitted encrypted data packet,the encrypted serial data does not include a part in which undesiredinhibited codes are converted into serial data.

The first code in the identification data representing a type of theencrypted information data is replaced with the second code that isother than the inhibited codes and that is different from the firstcode. Accordingly, when the receiving apparatus receiving thetransmitted encrypted data packet does not include decrypting means forthe encrypted information data included in the encrypted data packet,the type of the original information data represented by theidentification data before the replacement is not recognized and,therefore, the data provided as the reproduced information data based onthe encrypted information data included in the encrypted data packet isnot processed as data belonging to the type of the original informationdata represented by the identification data before the replacement.Consequently, for example, when the encrypted auxiliary data packet isan encrypted audio data packet including encrypted digital audioinformation data having encrypted digital audio information and thereceiving apparatus receiving the encrypted data packet has a speaker,serving as audio reproducing means for reproducing audio based on thereproduced digital audio information, but does not have the decryptingmeans for the encrypted information data included in the encrypted datapacket, no signal based on the encrypted information data is supplied tothe speaker and, therefore, an undesirable audio signal generated basedon the encrypted information data is not supplied to the speaker. As aresult, a situation in which an excessive current based on the undesiredaudio signal is applied to the speaker to damage the speaker can beavoided.

In the data transmission method according to the invention described inClaim 5 or the data transmission apparatus according to the inventiondescribed in Claim 11, the error correction data for the encryptedinformation data is generated along with the encrypted information dataand the encrypted information data and the error correction datacorresponding to the encrypted information data are included in theencrypted data packet. Accordingly, a situation in which the encryptioncauses a reduction in performance of the error correction of theencrypted information data can be avoided.

In the data transmission method according to the invention described inClaim 6 or the data transmission apparatus according to the inventiondescribed in Claim 12, the data packet is included in each of the datasequences and the encrypted data packet based on the data packet isformed for every data sequence. Accordingly, even when a streamconverter using an FIFO memory is used in the encryption in order toform an encrypted auxiliary data packet, a situation in which thewriting period for the FIFO memory is not sufficiently provided to emptythe FIFO memory does not arise. Consequently, a reduction in quality ofthe encryption security of the encrypted auxiliary data packet is notcaused.

With the data transmission method according to the invention describedin any of Claims 4 to 6 in the claims of this application or the datatransmission apparatus according to the invention described in any ofClaims 10 to 12 in the claims of this application, when the encrypted HDsignal including the encrypted auxiliary data packet is formed and theencrypted HD-SDI signal based on the encrypted HD signal is transmitted,it is possible to selectively perform the encryption for every auxiliarydata packet in each line of the Y data sequence and the P_(B)/P_(R) datasequence forming the HD signal, thus improving the flexibility in theactual use.

In the data transmission method according to the invention described inany of Claims 1 to 6 in the claims of this application or the datatransmission apparatus according to the invention described in any ofClaims 7 to 12 in the claims of this application, it is possible to formthe encrypted auxiliary data packet by the encryption of the auxiliarydata packet formed of the auxiliary data included in the HD signalforming the HD-SDI signal, to generate the encrypted HD signal includingthe encrypted auxiliary data packet, and to transmit the encryptedHD-SDI signal based on the encrypted HD signal while selectivelyperforming the encryption for every auxiliary data packet and avoidingthe disadvantages involved in the application of proposed technologiesdescribed above.

In the data reception method according to the invention described in anyof Claims 13 to 15 in the claims of this application or the datareception apparatus according to the invention described in any ofClaims 19 to 21 in the claims of this application, the encrypted datapacket that is transmitted, that includes the encrypted information dataincluding no inhibited codes, and that has the data flag formed of thesecond combination of a plurality of inhibited codes, with which secondcombination of the inhibited codes the first combination of theinhibited codes is replaced, the second combination being different fromthe first combination, is received; the decryption is performed for theencrypted information data included in the encrypted data packet togenerate the reproduced information data; the data flag included in theencrypted data packet is detected; and the reproduced information datais extracted in accordance with the detection output resulting from thedetection.

In the above process, the encrypted information data included in theencrypted data packet includes no inhibited codes. Accordingly, in thegeneration of encrypted serial data based on the transmitted encrypteddata packet, the encrypted serial data does not include a part in whichundesired inhibited codes are converted into serial data. Consequently,the reception of the encrypted data packet that is transmitted and thatincludes the encrypted information data including no inhibited codesdoes not have the disadvantage in that undesired inhibited codes aredetected and, therefore, the encrypted data packet is not received.

In addition, the decryption is performed for the encrypted informationdata including no inhibited codes, in the received encrypted datapacket, to generate the reproduced information data. The data flagformed of the first combination of the inhibited codes is replaced withthe second combination of the inhibited codes, the second combinationbeing different from the first combination, is detected and a timingwhen the reproduced information data is generated is detected based onthe detection output representing the reception of the encrypted datapacket. At a timing detected based on the detection output representingthe reception of the encrypted data packet, the reproduced informationdata resulting from the decryption performed for the encryptedinformation data is extracted. Accordingly, appropriate reproducedinformation-data can be reproduced.

In the data reception method according to the invention described in anyof Claims 16 to 18 in the claims of this application or the datareception apparatus according to the invention described in any ofClaims 22 to 24 in the claims of this application, the encrypted datapacket that is transmitted, that has the data flag formed of theinhibited codes, and that includes the encrypted information dataincluding no inhibited codes, the data flag being followed by theidentification data that has the second code other than the inhibitedcodes, with which second code the first code is replaced, the secondcode being different from the first code, is received; the decryption isperformed for the encrypted information data included in the encrypteddata packet to generate the reproduced information data; theidentification data included in the encrypted data packet is detected;and the reproduced information data is extracted in accordance with thedetection output resulting from the detection.

In the above process, the encrypted information data included in theencrypted data packet includes no inhibited codes. Accordingly, in thegeneration of encrypted serial data based on the transmitted encrypteddata packet, the encrypted serial data does not include a part in whichundesired inhibited codes are converted into serial data. Consequently,the reception of the encrypted data packet that is transmitted and thatincludes the encrypted information data including no inhibited codesdoes not have the disadvantage in that undesired inhibited codes aredetected and, therefore, the encrypted data packet is not received.

In addition, the decryption is performed for the encrypted informationdata including no inhibited codes, in the received encrypted datapacket, to generate the reproduced information data. The identificationdata having the second code other than the inhibited codes, differentfrom the original first code, with which second code the first code isreplaced, is detected and a timing when the reproduced information datais generated is detected based on the detection output representing thetiming corresponding to the position of the identification data in theencrypted data packet. At the detected timing, the reproducedinformation data resulting from the decryption performed for theencrypted information data is extracted. Accordingly, appropriatereproduced information data can be reproduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 includes conceptual diagrams illustrating an example of a dataformat of an HD signal.

FIG. 2 includes conceptual diagrams illustrating a data format of anauxiliary data packet formed of auxiliary data in the HD signal.

FIG. 3 is a conceptual diagram illustrating a data format of an audiodata packet formed of digital audio auxiliary data in the HD signal.

FIG. 4 is a conceptual diagram illustrating another example of the dataformat of the HD signal.

FIG. 5 is a block diagram showing an example of a data transmissionapparatus according to the invention described in any of Claims 7 to 12in the claims of this application, implementing an example of a datatransmission method according to the invention described in any ofClaims 1 to 6 in the claims of this application.

FIG. 6 is a conceptual diagram showing a data format used in thedescription of the example of the data transmission apparatus shown inFIG. 5.

FIG. 7 is a conceptual diagram showing another data format used in thedescription of the example of the data transmission apparatus shown inFIG. 5.

FIG. 8 is a block diagram showing an example of the structure of aY-series auxiliary-information-data formatting unit shown in FIG. 5.

FIG. 9 is a block diagram showing another example of the structure ofthe Y-series auxiliary-information-data formatting unit shown in FIG. 5.

FIG. 10 is a block diagram showing yet another example of the structureof the Y-series auxiliary-information-data formatting unit shown in FIG.5.

FIG. 11 is a block diagram showing another example of the datatransmission apparatus according to the invention described in any ofClaims 7 to 12 in the claims of this application, implementing anexample of the data transmission method according to the inventiondescribed in any of Claims 1 to 6 in the claims of this application.

FIG. 12 is a block diagram showing an example of a data receptionapparatus according to the invention described in any of Claims 19 to 24in the claims of this application, implementing an example of a datareception method according to the invention described in any of Claims13 to 18 in the claims of this application.

FIG. 13 is a block diagram showing an example of the structure of aY-series auxiliary-information-data decoding-extracting unit shown inFIG. 12.

FIG. 14 is a block diagram showing another example of the structure ofthe Y-series auxiliary-information-data decoding-extracting unit shownin FIG. 12.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 5 shows an example of a data transmission apparatus according tothe invention described in any of Claims 7 to 12 in the claims of thisapplication, implementing an example of a data transmission methodaccording to the invention described in any of Claims 1 to 6 in theclaims of this application.

Referring to FIG. 5, the data transmission apparatus includes a datastorage unit 11 storing Y-series video data and Y-series auxiliaryinformation data, which forms the Y data sequence in an HD signal, andP_(B)/P_(R)-series video data and P_(B)/P_(R)-series auxiliaryinformation data, which forms the P_(B)/P_(R) data sequence in the HDsignal. The Y-series video data, the P_(B)/P_(R)-series auxiliaryinformation data, the Y-series auxiliary information data, and theP_(B)/P_(R)-series auxiliary information data are formed of, forexample, 10-bit words. The data storage unit 11 is connected to anexternal data source via an input-output interface (I/F) 12.

A timing control signal Ta is supplied from a timing control signalgenerator 14 controlled by a system controller 13 controlling the entiredata transmission apparatus to the data storage unit 11. The datastorage unit 11 transmits Y-series video data DYV, P_(B)/P_(R)-seriesvideo data DCV, Y-series auxiliary information data DYA, andP_(B)/P_(R)-series auxiliary information data DCA at the timingspecified by the timing control signal Ta. The Y-series auxiliaryinformation data DYA and the P_(B)/P_(R)-series auxiliary informationdata DCA are, for example, digital audio information data.

The Y-series video data DYV, the P_(B)/P_(R)-series video data DCV, theY-series auxiliary information data DYA, and the P_(B)/P_(R)-seriesauxiliary information data DCA are supplied from the data storage unit11 to a Y-series video-data formatting unit 15, a P_(B)/P_(R)-seriesvideo-data formatting unit 16, a Y-series auxiliary-information-dataformatting unit 17, and a P_(B)/P_(R)-series auxiliary-information-dataformatting unit 18, respectively. Key data DKYV used for encrypting theY-series video data, key data DKCV used for encrypting theP_(B)/P_(R)-series video data, key data DKYA used for encrypting theY-series auxiliary information data, and key data DKCA used forencrypting the P_(B)/P_(R)-series auxiliary information data are alsosupplied from a key data generator 19 to the Y-series video-dataformatting unit 15, the P_(B)/P_(R)-series video-data formatting unit16, the Y-series auxiliary-information-data formatting unit 17, and theP_(B)/P_(R)-series auxiliary-information-data formatting unit 18,respectively. Timing control signals Tc, Td, Te, and Tf are alsosupplied from the timing control signal generator 14 to the Y-seriesvideo-data formatting unit 15, the P_(B)/P_(R)-series video-dataformatting unit 16, the Y-series auxiliary-information-data formattingunit 17, and the P_(B)/P_(R)-series auxiliary-information-dataformatting unit 18, respectively.

A timing control signal Tb is supplied from the timing control signalgenerator 14 to the key data generator 19. The key data generator 19transmits the key data DKYV, DKCV, DKYA, and DKCA at the timingspecified by the timing control signal Tb.

In the Y-series video-data formatting unit 15, the encryption by usingthe key data DKYV is performed by, for example, the AES method for theY-series video data DYV in accordance with the timing control signal Tcso as not to generate inhibited codes (000h to 003h and 3FCh to 3FFh) inorder to generate encrypted Y-series video data DYVE that is based onthe Y-series video data DYV and that includes no inhibited codes.Similarly, in the P_(B)/P_(R)-series video-data formatting unit 16, theencryption by using the key data DKCV is performed by, for example, theAES method for the P_(B)/P_(R)-series video data DCV in accordance withthe timing control signal Td so as not to generate inhibited codes inorder to generate encrypted P_(B)/P_(R)-series video data DCVE that isbased on the P_(B)/P_(R)-series video data DCV and that includes noinhibited codes.

In the Y-series auxiliary-information-data formatting unit 17, there arecases in which the Y-series auxiliary information data DYA is to beencrypted or is not to be encrypted.

When the Y-series auxiliary information data DYA is to be encrypted, theencryption by using the key data DKYA is performed by, for example, theAES method for the Y-series auxiliary information data DYA in accordancewith the timing control signal Te so as not to generate inhibited codesin order to generate encrypted Y-series auxiliary information data DYAEthat is based on the Y-series auxiliary information data DYA and thatincludes no inhibited codes. Since the Y-series auxiliary informationdata DYA is digital audio information data in the example in FIG. 5, theencrypted Y-series auxiliary information data DYAE is encrypted digitalaudio information data. In the Y-series auxiliary-information-dataformatting unit 17, the ADF (auxiliary data flag), the DID (dataidentification word), the DBN (data block number word), the DC (datacount word), and the CS (checksum word) are added in this order to thegenerated encrypted Y-series auxiliary information data DYAE to form anencrypted Y-series auxiliary data packet PYAE, which starts from the ADFand which includes the encrypted Y-series auxiliary information dataDYAE as an encrypted audio data packet.

The ADF or DID is replaced with the one different from the original. ADFor DID in the Y-series auxiliary-information-data formatting unit 17.

The ADF is replaced with the one different from the original ADF in thefollowing manner.

The ADF has continuous three words arranged therein, which are acombination of [000h, 3FFh, and 3FFh] and to which the inhibited codesare set. When the Y-series auxiliary information data DYA is to beencrypted, the ADF is replaced with the one having continuous multiplewords arranged therein, which are a combination (a second combination)different from the combination of [000h, 3FFh, and 3FFh] (a firstcombination) and to which the inhibited codes are set (the replaced ADFis hereinafter referred to as EADF). The second combination of the EADF,which is the ADF subjected to the replacement described above, is, forexample, [000h, 3FEh, 3FEh], [003h, 3FCh, 000h], [000h, 3FEh, 3FEh,3FEh].

Accordingly, the encrypted Y-series auxiliary data packet PYAE generatedwhen the encryption is performed for the Y-series auxiliary informationdata DYA in the Y-series auxiliary-information-data formatting unit 17has a three-word EADF, a one-word DID, a one-word DBN, a one-word DC, a24-word encrypted Y-series auxiliary information data DYAE, and aone-word CS sequentially arranged, as shown by reference letter A inFIG. 6.

The DID is replaced with the one different from the original DID in thefollowing manner.

The DID represents a type of the Y-series auxiliary information data andis set to a code other than the inhibited codes, set in advance inaccordance with the type of the auxiliary information data. When theY-series auxiliary information data DYA is to be encrypted, the DID isreplaced with the one which is set in advance in accordance with thetype of the auxiliary information data, which is different from a code(a first code) other than the inhibited codes, which is setcorresponding to the first code, and to which a code (a second code)other than the inhibited codes is set (the replaced DID is hereinafterreferred to as EDID). That is, the EDID resulting from the abovereplacement of the DID has the second code different from the originalfirst code.

Accordingly, the encrypted Y-series auxiliary data packet PYAE generatedwhen the encryption is performed for the Y-series auxiliary informationdata DYA in the Y-series auxiliary-information-data formatting unit 17has a three-word ADF, the one-word EDID, a one-word DBN, a one-word DC,a 24-word encrypted Y-series auxiliary information data DYAE, and aone-word CS sequentially arranged, as shown by reference letter A inFIG. 7.

In contrast, when the Y-series auxiliary information data DYA is not tobe encrypted, the ADF, the DID, the DBN, the DC, and the CS are added inthis order to the Y-series auxiliary information data DYA to form aY-series auxiliary data packet PYA, which starts from the ADF and whichincludes the Y-series auxiliary information data DYA, as an audio datapacket. In this case, the ADF is not subjected to the replacementdescribed above and has continuous three words arranged therein, whichare the original combination of [000h, 3FFh, 3FFh] and to which theinhibited codes are set. The DID is also not subjected to thereplacement described above and is set to a code which is set in advancein accordance with the type of the original auxiliary information dataand to which a code other than the inhibited codes is set.

In the P_(B)/P_(R)-series auxiliary-information-data formatting unit 18,there are cases in which the P_(B)/P_(R)-series auxiliary informationdata DCA is to be encrypted or is not to be encrypted.

When the P_(B)/P_(R)-series auxiliary information data DCA is to beencrypted, the encryption by using the key data DKCA is performed by,for example, the AES method for the P_(B)/P_(R)-series auxiliaryinformation data DCA in accordance with the timing control signal Tf soas not to generate inhibited codes in order to generate encryptedP_(B)/P_(R)-series auxiliary information data DCAE that is based on theP_(B)/P_(R)-series auxiliary information data DCA and that includes noinhibited codes. Since the P_(B)/P_(R)-series auxiliary information dataDCA is digital audio information data in the example in FIG. 5, theencrypted P_(B)/P_(R)-series auxiliary information data DCAE isencrypted digital audio information data. In the P_(B)/P_(R)-seriesauxiliary-information-data formatting unit 18, the ADF, the DID, theDBN, the DC, and the CS are added in this order to the generatedencrypted P_(B)/P_(R)-series auxiliary information data DCAE to form anencrypted P_(B)/P_(R)-series auxiliary data packet PCAE, which startsfrom the ADF and which includes the encrypted P_(B)/P_(R)-seriesauxiliary information data DCAE, as an encrypted audio data packet.

The ADF or DID is replaced with the one different from the original ADFor DID in the P_(B)/P_(R)-series auxiliary-information-data formattingunit 18.

When the ADF is to be replaced with the one different from the originalADF, the EADF subjected to the replacement described above is usedinstead of the ADF having continuous three words arranged therein, whichare the original combination of [000h, 3FFh, 3FFh] and to which theinhibited codes are set, as in the encryption of the Y-series auxiliaryinformation data DYA described above.

Accordingly, the encrypted P_(B)/P_(R)-series auxiliary data packet PCAEgenerated when the encryption is performed for the P_(B)/P_(R)-seriesauxiliary information data DCA in the P_(B)/P_(R)-seriesauxiliary-information-data formatting unit 18 has a three-word EADF, aone-word DID, a one-word DBN, a one-word DC, the 24-word encryptedP_(B)/P_(R)-series auxiliary information data DCAE, and a one-word CSsequentially arranged, as shown by reference letter B in FIG. 6.

When the DID is to be replaced with the one different from the originalDID, the EDID subjected to the replacement described above is usedinstead of the DID, which is set in advance in accordance with the typeof the original auxiliary information data and to which a code otherthan the inhibited codes is set, as in the encryption of the Y-seriesauxiliary information data DYA described above.

Accordingly, the encrypted P_(B)/P_(R)-series auxiliary data packet PCAEgenerated when the encryption is performed for the P_(B)/P_(R)-seriesauxiliary information data DCA in the P_(B)/P_(R)-seriesauxiliary-information-data formatting unit 18 has a three-word ADF, theone-word EDID, a one-word DBN, a one-word DC, a 24-word encryptedP_(B)/P_(R)-series auxiliary information data DCAE, and a one-word CSsequentially arranged, as shown by reference letter B in FIG. 7.

In contrast, when the P_(B)/P_(R)-series auxiliary information data DCAis not to be encrypted, the ADF, the DID, the DBN, the DC, and the CSare added in this order to the P_(B)/P_(R)-series auxiliary informationdata DCA to form a P_(B)/P_(R)-series auxiliary data packet PCA, whichstarts from the ADF and which includes the P_(B)/P_(R)-series auxiliaryinformation data DCA, as an audio data packet. In this case, the ADF isnot subjected to the replacement described above and has continuousthree words arranged therein, which are the original combination of[000h, 3FFh, 3FFh] and to which the inhibited codes are set. The DID isalso not subjected to the replacement described above and is set to acode which is set in advance in accordance with the type of the originalauxiliary information data and to which a code other than the inhibitedcodes is set.

The encrypted Y-series video data DYVE from the Y-series video-dataformatting unit 15, the encrypted P_(B)/P_(R)-series video data DCVEfrom the P_(B)/P_(R)-series video-data formatting unit 16, the encryptedY-series auxiliary data packet PYAE or the Y-series auxiliary datapacket PYA from the Y-series auxiliary-information-data formatting unit17, and the encrypted P_(B)/P_(R)-series auxiliary data packet PCAE orthe P_(B)/P_(R)-series auxiliary data packet PCA from theP_(B)/P_(R)-series auxiliary-information-data formatting unit 18 aresupplied to a data transmitting unit 20. A timing control signal Tg isalso supplied from the timing control signal generator 14 to the datatransmitting unit 20.

The data transmitting unit 20 includes a data synthesizer 21 to whichthe encrypted Y-series video data DYVE, the encrypted P_(B)/P_(R)-seriesvideo data DCVE, the encrypted Y-series auxiliary data packet PYAE orthe Y-series auxiliary data packet PYA, the encrypted P_(B)/P_(R)-seriesauxiliary data packet PCAE or the P_(B)/P_(R)-series auxiliary datapacket PCA, and the timing control signal Tg are supplied. The datasynthesizer 21 synthesizes the encrypted Y-series video data DYVE, theencrypted P_(B)/P_(R)-series video data DCVE, the encrypted Y-seriesauxiliary data packet PYAE or the Y-series auxiliary data packet PYA,and the encrypted P_(B)/P_(R)-series auxiliary data packet PCAE or theP_(B)/P_(R)-series auxiliary data packet PCA under the control of thetiming control signal Tg, and the timing reference code data EAV, theline number data, the error detection code data, the timing referencecode data SAV, etc., described above, are added to the synthesizedresult to form an encrypted HD signal DXP.

The encrypted HD signal DXP formed in the data synthesizer 21 is formedof an encrypted Y data sequence and an encrypted P_(B)/P_(R) datasequence. In each line of the encrypted Y data sequence, the lineblanking area including, for example, the timing reference code dataEAV, the line number data, the error detection code data, the encryptedY-series auxiliary data packet PYAE or the Y-series auxiliary datapacket PYA, and the timing reference code data SAV is followed by theencrypted Y-series video data DYVE. In each line of the encryptedP_(B)/P_(R) data sequence, the line blanking area including, forexample, the timing reference code data EAV, the line number data, theerror detection code data, the encrypted P_(B)/P_(R)-series auxiliarydata packet PCAE or the P_(B)/P_(R)-series auxiliary data packet PCA,and the timing reference code data SAV is followed by the encryptedP_(B)/P_(R)-series video data DCVE.

A parallel-to-serial (P/S) converter 22 converts the encrypted HD signalDXP supplied from the data synthesizer 21 into serial data to generateencrypted serial data DXSD. A scramble processor 23 performs scramblingfor the encrypted serial data DXSD to generate scrambled and encryptedserial data DXSC. A NRZI converter 24 performs non return to zeroinverted (NRZI) conversion to generate an encrypted HD-SDI signal DXS.The encrypted HD-SDI signal DXS supplied from the NRZI converter 24 issupplied to a data transmission path 26 through a transmission drive 25and is transmitted.

The data transmitting unit 20 including the data synthesizer 21, P/Sconverter 22, the scramble processor 23, the NRZI converter 24, and thetransmission drive 25 transmits the encrypted Y-series video data DYVEsupplied from the Y-series video-data formatting unit 15, the encryptedP_(B)/P_(R)-series video data DCVE supplied from the P_(B)/P_(R)-seriesvideo-data formatting unit 16, the encrypted Y-series auxiliary datapacket PYAE or the Y-series auxiliary data packet PYA supplied from theY-series auxiliary-information-data formatting unit 17, and theencrypted P_(B)/P_(R)-series auxiliary data packet PCAE or theP_(B)/P_(R)-series auxiliary data packet PCA supplied from theP_(B)/P_(R)-series auxiliary-information-data formatting unit 18.

FIG. 8 shows an example of the structure of the Y-seriesauxiliary-information-data formatting unit 17. In the example of thestructure shown in FIG. 8, the Y-series auxiliary information data DYAis supplied to both an encryption processor 31 and a delay device 32.The key data DKYA is supplied to a key data converter 33. The timingcontrol signal Te is supplied to a control signal generator 34. Thecontrol signal generator 34 transmits control signals TA, TB, TC, and TDhaving different functions in response to the timing control signal Teor in accordance with other setting conditions.

The control signal TA is supplied from the control signal generator 34to the key data converter 33. The key data converter 33 transmits pseudorandom number data DYYA formed based on the key data DKYA at a timingcorresponding to the control signal TA and supplies the pseudo randomnumber data DYYA to the encryption processor 31.

The encryption processor 31 performs the encryption by using the pseudorandom number data DYYA supplied from the key data converter 33 for theY-series auxiliary information data DYA to generate the encryptedY-series auxiliary information data DYAE that is based on the Y-seriesauxiliary information data DYA and that includes no inhibited codes, andsupplies the generated encrypted Y-series auxiliary information dataDYAE to a data selector 35.

The delay device 32 delays the Y-series auxiliary information data DYAby a time corresponding to the time required for the encryption of theY-series auxiliary information data DYA in the encryption processor 31,and supplies the delayed Y-series auxiliary information data DYA to thedata selector 35.

The control signal TC is supplied from the control signal generator 34to the data selector 35. The control signal TC selectively indicateswhether the auxiliary information data is to be encrypted or not to beencrypted. The data selector 35 extracts the encrypted Y-seriesauxiliary information data DYAE supplied from the encryption processor31 when the control signal TC indicates that the auxiliary informationdata is to be encrypted, and extracts the Y-series auxiliary informationdata DYA supplied from the delay device 32 when the control signal TCindicates that the auxiliary information data is not to be encrypted.The encrypted Y-series auxiliary information data DYAE or the Y-seriesauxiliary information data DYA selectively extracted by the dataselector 35 is supplied to a data-packet generating section 36.

The data-packet generating section 36 supplies the encrypted Y-seriesauxiliary information data DYAE or the Y-series auxiliary informationdata DYA from the data selector 35 to a data selector 37. The controlsignal TD is supplied from the control signal generator 34 to the dataselector 37. The control signal TD indicates a timing when the auxiliaryinformation data is to be generated and a timing when a variety of codedata required for forming the auxiliary data packet, other than theauxiliary information data, is to be generated, in the generation of theauxiliary data packet.

The data-packet generating section 36 includes a packet-code-datagenerator 38 transmitting the variety of code data ADF, DID, DBN, DC,and CS required for forming the auxiliary data packet as packet codedata DPC. The control signals TB and TC are supplied from the controlsignal generator 34 to the packet-code-data generator 38.

The packet-code-data generator 38 transmits the ADF, DID, DBN, DC, andCS as the packet code data DPC at a timing corresponding to the controlsignal TB and supplies the packet code data DPC to the data selector 37.When the control signal TC indicates that the auxiliary information datais to be encrypted, the packet-code-data generator 38 is in a state inwhich the EADF subjected to the replacement described above istransmitted instead of the original ADF or is in a state in which theEDID subjected to the replacement described above is transmitted insteadof the original DID. Whether the packet-code-data generator 38 is in thestate in which the EADF is transmitted instead of the ADF or is in thestate in which the EDID is transmitted instead of the DID is set inadvance in the packet-code-data generator 38. In contrast, when thecontrol signal TC indicates that the auxiliary information data is notto be encrypted, the packet-code-data generator 38 transmits theoriginal ADF and DID.

The data selector 37 selects and extracts the packet code data DPCsupplied from the packet-code-data generator 38 when the control signalTD indicates the timing when the variety of code data required forforming the auxiliary data packet, other than the auxiliary informationdata, is to be generated, and extracts the encrypted Y-series auxiliaryinformation data DYAE or the Y-series auxiliary information data DYAsupplied from the data selector 35 when the control signal TD indicatesthe timing when the auxiliary information data is to be generated. As aresult, the encrypted Y-series auxiliary data packet PYAE having theEADF, the DID, the DBN, the DC, the encrypted Y-series auxiliaryinformation data DYAE, and the CS arranged in this order or having theADF, the EDID, the DBN, the DC, the encrypted Y-series auxiliaryinformation data DYAE, and the CS arranged in this order, or theY-series auxiliary data packet PYA having the ADF, the DID, the DBN, theDC, the Y-series auxiliary information data DYA, and the CS arranged inthis order is output from the data-packet generating section 36.

An example of the structure of the P_(B)/P_(R)-seriesauxiliary-information-data formatting unit 18 is similar to the exampleof the structure of the Y-series auxiliary-information-data formattingunit 17 shown in FIG. 8. In the example of the structure of theP_(B)/P_(R)-series auxiliary-information-data formatting unit 18, theencrypted P_(B)/P_(R)-series auxiliary data packet PCAE having the EADF,the DID, the DBN, the DC, the encrypted P_(B)/P_(R)-series auxiliaryinformation data DCAE, and the CS arranged in this order or having theADF, the EDID, the DBN, the DC, the encrypted P_(B)/P_(R)-seriesauxiliary information data DCAE, and the CS arranged in this order, orthe P_(B)/P_(R)-series auxiliary data packet PCA having the ADF, theDID, the DBN, the DC, the P_(B)/P_(R)-series auxiliary information dataDCA, and the CS arranged in this order is output from a data-packetgenerating section corresponding to the data-packet generating section36 shown in FIG. 8.

FIG. 9 shows another example of the structure of the Y-seriesauxiliary-information-data formatting unit 17. The example of thestructure shown in FIG. 9 has many components similar to those in theexample of the structure shown in FIG. 8, and the same referencenumerals are used in FIG. 9 to identify the same components and datashown in FIG. 8. A duplicated description of such components and data isomitted herein.

In the example of the structure in FIG. 9, the control signal generator34 transmits control signals TE and TF, in addition to the controlsignals TA, TB, TC, and TD. The data-packet generating section 36includes an error-correction-data generator 39 and a data selector 40,in addition to the data selector 37 and the packet-code-data generator38.

The data selector 37 in The data-packet generating section 36 selectsand extracts the packet code data DPC supplied from the packet-code-datagenerator 38 when the control signal TD indicates the timing when thevariety of code data required for forming the auxiliary data packet,other than the auxiliary information data, is to be generated, andextracts the encrypted Y-series auxiliary information data DYAE or theY-series auxiliary information data DYA supplied from the data selector35 when the control signal TD indicates the timing when the auxiliaryinformation data is to be generated. As a result, encrypted wordsequence data QYAE having the EADF, the DID, the DBN, the DC, theencrypted Y-series auxiliary information data DYAE, and the CS arrangedin this order or having the ADF, the EDID, the DBN, the DC, theencrypted Y-series auxiliary information data DYAE, and the CS arrangedin this order, or word sequence data QYA having the ADF, the DID, theDBN, the DC, the Y-series auxiliary information data DYA, and the CSarranged in this order is output from the data selector 37. Theencrypted word sequence data QYAE or the word sequence data QYA outputfrom the data selector 37 is supplied to the data selector 40.

The control signal TE is supplied from the control signal generator 34to the error-correction-data generator 39 in the data-packet generatingsection 36. The control signal TE indicates that error correction datais to be generated. The control signal TF is supplied from the controlsignal generator 34 to the data selector 40 in the data-packetgenerating section 36. The control signal TF indicates a timing when theerror correction data is inserted into the auxiliary data packet in theformation of the auxiliary data packet.

The encrypted Y-series auxiliary information data DYAE or the Y-seriesauxiliary information data DYA is supplied from the data selector 35 tothe error-correction-data generator 39. When the encrypted Y-seriesauxiliary information data DYAE is supplied to the error-correction-datagenerator 39, the error-correction-data generator 39 generates errorcorrection data DECE for the encrypted Y-series auxiliary informationdata DYAE in response to the control signal TE and supplies the formederror correction data DECE to the data selector 40. When the Y-seriesauxiliary information data DYA is supplied to the error-correction-datagenerator 39, the error-correction-data generator 39 generates errorcorrection data DEC for the Y-series auxiliary information data DYA inresponse to the control signal TE and supplies the error correction dataDEC to the data selector 40.

The data selector 40 selects and extracts the error correction data DECEor DEC supplied from the error-correction-data generator 39 when thecontrol signal TF indicates a timing when the error correction data isinserted into the auxiliary data packet and, otherwise, extracts theencrypted word sequence data QYAE or the word sequence data QYA suppliedfrom the data selector 37. As a result, the encrypted Y-series auxiliarydata packet PYAE that is based on the encrypted word sequence data QYAEand the error correction data DECE and that has the EADF, the DID, theDBN, the DC, the encrypted Y-series auxiliary information data DYAE, theerror correction data DECE, and the CS arranged in this order or has theADF, the EDID, the DBN, the DC, the encrypted Y-series auxiliaryinformation data DYAE, the error correction data DECE, and the CSarranged in this order, or the Y-series auxiliary data packet PYA thatis based on the word sequence data QYA and the error correction data DECand that has the ADF, the DID, the DBN, the DC, the Y-series auxiliaryinformation data DYA, the error correction data DEC, and the CS arrangedin this order is output from the data-packet generating section 36.

Another example of the structure of the P_(B)/P_(R)-seriesauxiliary-information-data formatting unit 18 is similar to the otherexample of the structure of the Y-series auxiliary-information-dataformatting unit 17 shown in FIG. 9. In the other example of thestructure of the P_(B)/P_(R)-series auxiliary-information-dataformatting unit 18, the encrypted P_(B)/P_(R)-series auxiliary datapacket PCAE having the EADF, the DID, the DBN, the DC, the encryptedP_(B)/P_(R)-series auxiliary information data DCAE, the error correctiondata DECE, and the CS arranged in this order or having the ADF, theEDID, the DBN, the DC, the encrypted P_(B)/P_(R)-series auxiliaryinformation data DCAE, the error correction data DECE, and the CSarranged in this order, or the P_(B)/P_(R)-series auxiliary data packetPCA having the ADF, the DID, the DBN, the DC, the P_(B)/P_(R)-seriesauxiliary information data DCA, the error correction data DEC, and theCS arranged in this order is output from a data-packet generatingsection corresponding to the data-packet generating section 36 shown inFIG. 9.

When the Y-series auxiliary-information-data formatting unit 17 has thestructure shown in FIG. 9 and the P_(B)/P_(R)-seriesauxiliary-information-data formatting unit 18 has the structure similarto the structure shown in FIG. 9, the encrypted Y-series auxiliary datapacket PYAE includes the error correction data DECE formed for theencrypted Y-series auxiliary information data DYAE, and theP_(B)/P_(R)-series auxiliary data packet PCA includes the errorcorrection data DECE formed for the encrypted P_(B)/P_(R)-seriesauxiliary information data DCAE. Accordingly, a reduction in performanceof the error correction, caused by the encryption, in the encryptedY-series auxiliary information data DYAE and the encryptedP_(B)/P_(R)-series auxiliary information data DCAE can be avoided.

FIG. 10 shows yet another example of the structure of the Y-seriesauxiliary-information-data formatting unit 17. Part of the example ofthe structure shown in FIG. 10 is similar to the example of thestructure shown in FIG. 8, and the same reference numerals are used inFIG. 10 to identify the same components and data shown in FIG. 8. Aduplicated description of such components and data is omitted herein.

In the example of the structure shown in FIG. 10, the Y-series auxiliaryinformation data DYA is digital audio information data. In each word inthe digital audio information data, eight bits excluding the higher twobits among the 10 bits serve as the information bits, as describedabove, and the higher two bits are set to “10” or “01”.

The Y-series auxiliary information data DYA, which is digital audioinformation data, is supplied to a bit divider 41. The bit divider 41performs bit division in which the 10 bits in each word are divided intothe lower eight bits and the higher two bits (“10” or “01”) for theY-series auxiliary information data DYA to form eight-bit string dataDY8 including the eight bits resulting from the division of each word inthe Y-series auxiliary information data DYA and two-bit string data DY2including the two bits resulting from the division of each word of theY-series auxiliary information data DYA. The eight-bit string data DY8formed in the bit divider 41 is supplied to both an encryption processor42 and a delay device 43, and the two-bit string data DY2 formed in thebit divider 41 is supplied to a bit adder 45.

The encryption processor 42 includes, for example, a bit-wise exclusiveOR circuit. The key data DKYA is supplied to the encryption processor42, in addition to the eight-bit string data DY8. The encryptionprocessor 42 performs encryption by using the key data DKYA for theeight-bit string data DY8 to form encrypted 8-bit string data DY8E, andsupplies the encrypted 8-bit string data DY8E to a data selector 44.

The delay device 43 delays the eight-bit string data DY8 by a timecorresponding to the time required for the encryption of the eight-bitstring data DY8 in the encryption processor 42, and supplies the delayedeight-bit string data DY8 to the data selector 44.

The control signal TC is supplied from the control signal generator 34to the data selector 44. The data selector 44 extracts the encrypted8-bit string data DY8E supplied from the encryption processor 42 whenthe control signal TC indicates that the auxiliary information data isto be encrypted, and extracts the eight-bit string data DY8 suppliedfrom the encryption processor 42 when the control signal TC indicatesthat the auxiliary information data is not to be encrypted. Theencrypted 8-bit string data DY8E or the eight-bit string data DY8selectively extracted by the data selector 44 is supplied to the bitadder 45.

The bit adder 45 adds the two bits, that is, X“10” or “01”, in thetwo-bit string data DY2 supplied from the bit divider 41 to the eightbits in the encrypted 8-bit string data DY8E or to the eight-bit stringdata DY8 supplied from the data selector 44 to generate a 10-bit word.The inhibited codes are not set to the 10-bit word structured in theabove manner because the higher two bits are set to “10” or “01”. Theencrypted Y-series auxiliary information data DYAE or Y-series auxiliaryinformation data DYA, which is generated in the bit adder 45, whichincludes the 10-bit words, and to which the inhibited codes are not set,is supplied to a data-packet generating section 36.

The data-packet generating section 36 corresponds to the data-packetgenerating section 36 in the example of the structure shown in FIG. 8.As in the example of the structure in FIG. 8, the encrypted Y-seriesauxiliary data packet PYAE or Y-series auxiliary data packet PYA isoutput from the data-packet generating section 36.

Yet another example of the structure of the P_(B)/P_(R)-seriesauxiliary-information-data formatting unit 18 is similar to the otherexample of the structure of the Y-series auxiliary-information-dataformatting unit 17 shown in FIG. 10. In the other example of thestructure of the P_(B)/P_(R)-series auxiliary-information-dataformatting unit 18, the encrypted P_(B)/P_(R)-series auxiliary datapacket PCAE or P_(B)/P_(R)-series auxiliary data packet PCA is outputfrom a data-packet generating section corresponding to the data-packetgenerating section 36 in FIG. 10.

FIG. 11 shows another example of the data transmission apparatusaccording to the invention described in any of Claims 7 to 12 in theclaims of this application, implementing another example of the datatransmission method according to the invention described in any ofClaims 1 to 6 in the claims of this application.

The example in FIG. 11 has many components similar to those in theexample shown in FIG. 5, and the same reference numerals are used inFIG. 11 to identify the same components and data shown in FIG. 5. Aduplicated description of such components and data is omitted herein.

In the example shown in FIG. 11, an HD-SDI signal DSI, which is an inputsignal, is supplied to a NRZI demodulator 51. The NRZI demodulator 51performs NRZI demodulation for the HD-SDI signal DSI to generatescrambled serial data DSIC and supplies the scrambled serial data DSICto a descrambler 52.

The descrambler 52 performs descrambling for the scrambled serial dataDSIC to generated descrambled serial data DSID. The descrambled serialdata DSID is supplied from the descrambler 52 to both aserial-to-parallel (S/P) converter 53 and a synchronization patterndetector 54.

The synchronization pattern detector 54 detects a synchronizationpattern, which is a serial sequence of the inhibited codes, for example,[3FFh, 000h, 000h], in the serial data DSID to generate a detectionoutput signal SS of the synchronization pattern, and supplies thedetection output signal SS to the S/P converter 53. The S/P converter 53performs S/P conversion for the serial data DSID by using the detectionoutput signal SS supplied from the synchronization pattern detector 54to generate an HD signal DPI formed of a sequence of 10-bit words, basedon the serial data DSID. The HD signal DPI generated in the S/Pconverter 53 is supplied to a data partitioner 55.

The data partitioner 55 performs word partition for the HD signal DPI toseparate Y-series video data, P_(B)/P_(R)-series video data, Y-seriesauxiliary information data, and P_(B)/P_(R)-series auxiliary informationdata included in the HD signal DPI from each other and to extract theseparated data and packets. The data partitioner 55 transmits theY-series video data DYV, the P_(B)/P_(R)-series video data DCV, theY-series auxiliary information data DYA, and the P_(B)/P_(R)-seriesauxiliary information data DCA. The Y-series video data DYV, theP_(B)/P_(R)-series video data DCV, the Y-series auxiliary informationdata DYA, and the P_(B)/P_(R)-series auxiliary information data DCA aresupplied to a Y-series video-data formatting unit 15, aP_(B)/P_(R)-series video-data formatting unit 16, a Y-seriesauxiliary-information-data formatting unit 17, and a P_(B)/P_(R)-seriesauxiliary-information-data formatting unit 18, respectively.

Other structures and the operation in the example shown in FIG. 11 aresimilar to those in the example shown in FIG. 8. The encrypted HD-SDIsignal DXS is supplied from a data transmitting unit 20 to a datatransmission path 26 and is transmitted.

FIG. 12 shows an example of a data reception apparatus according to theinvention described in any of Claims 19 to 24 in the claims of thisapplication, implementing an example of a data reception methodaccording to the invention described in any of Claims 13 to 18 in theclaims of this application.

The example shown in FIG. 12 receives the encrypted HD-SDI signal DXStransmitted from the example of the data transmission apparatusaccording to the invention described in any of Claims 7 to 12 in theclaim of this application, shown in FIG. 5 or FIG. 11.

In the example shown in FIG. 12, the encrypted HD-SDI signal DXStransmitted through the data transmission path 26 is supplied to adata-sequence reproducing unit 61. In the data-sequence reproducing unit61, the encrypted HD-SDI signal DXS is supplied to an NRZI demodulator63 through an equalizer-clock recovery device 62.

The equalizer-clock recovery device 62 performs equalization forcompensating a variation in level caused in the transmission through thedata transmission path 26 for the encrypted HD-SDI signal DXS, andrecovers a clock signal in the encrypted HD-SDI signal DXS. The NRZIdemodulator 63 performs the NRZI modulation for the encrypted HD-SDIsignal DXS to generate scrambled serial data DXSC, and supplies thescrambled serial data DXSC to a descrambler 64.

The descrambler 64 performs descrambling for the scrambled serial dataDXSC to generated descrambled serial data DXSD. The descrambled serialdata DXSD is supplied from the descrambler 64 to both an S/P converter65 and to a synchronization pattern detector 66.

The synchronization pattern detector 66 detects a synchronizationpattern, which is a serial sequence of the inhibited codes, for example,[3FFh, 000h, 000h], in the serial data DXSD, to generate a detectionoutput signal SX of the synchronization pattern, and supplies thedetection output signal Sx to the S/P converter 65. The S/P converter 65performs the S/P conversion for the serial data DXSD by using thedetection output signal SX supplied from the synchronization patterndetector 66 to generate an encrypted HD signal DXP formed of a sequenceof 10-bit words, based on the serial data DXSD. The encrypted HD signalDXP generated in the S/P converter 65 is supplied to a data partitioner67.

The data partitioner 67 performs word partition for the encrypted HDsignal DXP to separate the encrypted Y-series video data DYVE, theencrypted P_(B)/P_(R)-series video data DCVE, the encrypted Y-seriesauxiliary data packet PYAE or the Y-series auxiliary data packet PYA,and the encrypted P_(B)/P_(R)-series auxiliary data packet PCAE or theP_(B)/P_(R)-series auxiliary data packet PCA included in the encryptedHD signal DXP from each other and to extract the separated data andpackets. The encrypted Y-series video data DYVE, the encryptedP_(B)/P_(R)-series video data DCVE, the encrypted Y-series auxiliarydata packet PYAE or the Y-series auxiliary data packet PYA, and theencrypted P_(B)/P_(R)-series auxiliary data packet PCAE or theP_(B)/P_(R)-series auxiliary data packet PCA, which are supplied fromthe data partitioner 67, are transmitted from the data-sequencereproducing unit 61 to a Y-series video-data decrypting unit 68, aP_(B)/P_(R)-series video-data decrypting unit 69, a Y-seriesauxiliary-information-data decrypting-extracting unit 70, and aP_(B)/P_(R)-series auxiliary-information-data decrypting-extracting unit71, respectively.

Key data DKYV used for decrypting the Y-series video data, key data DKCVused for decrypting the P_(B)/P_(R)-series video data, key data DKYAused for decrypting the Y-series auxiliary information data, and keydata DKCA used for decrypting the P_(B)/P_(R)-series auxiliaryinformation data are also supplied from a key data generator 72 to theY-series video-data decrypting unit 68, the P_(B)/P_(R)-seriesvideo-data decrypting unit 69, the Y-series auxiliary-information-datadecrypting-extracting unit 70, and the P_(B)/P_(R)-seriesauxiliary-information-data decrypting-extracting unit 71, respectively.Timing control signals Th, Ti, Tj, and Tk are also supplied from atiming control signal generator 73 to the -series video-data decryptingunit 68, the P_(B)/P_(R)-series video-data decrypting unit 69, theY-series auxiliary-information-data decrypting-extracting unit 70, andthe P_(B)/P_(R)-series auxiliary-information-data decrypting-extractingunit 71, respectively.

The timing control signal generator 73, to which the detection outputsignal SX is supplied from the synchronization pattern detector 66 inthe data-sequence reproducing unit 61, is controlled by a systemcontroller 74 controlling the entire data reception apparatus. The keydata generator 72 transmits the key data DKYV used for decrypting theY-series video data, the key data DKCV used for decrypting theP_(B)/P_(R)-series video data, the key data DKYA used for decrypting theY-series auxiliary information data, and the key data DKCA used fordecrypting the P_(B)/P_(R)-series auxiliary information data inaccordance with a timing control signal Tm supplied from the timingcontrol signal generator 73.

The Y-series video-data decrypting unit 68 performs decryption by usingthe key data DKYV for the encrypted Y-series video data DYVE inaccordance with the timing control signal Th to reproduce the Y-seriesvideo data DYV, which is based on the encrypted Y-series video data DYVEand which includes no inhibited codes. Similarly, the P_(B)/P_(R)-seriesvideo-data decrypting unit 69 performs the decryption by using the keydata DKCV for the encrypted P_(B)/P_(R)-series video data DCVE inaccordance with the timing control signal Ti to reproduce theP_(B)/P_(R)-series video data DCV, which is based on the encryptedP_(B)/P_(R)-series video data DCVE and which includes no inhibitedcodes.

The Y-series auxiliary-information-data decrypting-extracting unit 70performs the decryption by using the key data DKYA for the encryptedY-series auxiliary information data DYAE included in the encryptedY-series auxiliary data packet PYAE in accordance with the timingcontrol signal Tj to selectively enter a state in which the Y-seriesauxiliary information data DYA, which is based on the encrypted Y-seriesauxiliary information data DYAE and which includes no inhibited codes,is reproduced or a state in which the Y-series auxiliary informationdata DYA is extracted from the Y-series auxiliary data packet PYA.Similarly, the P_(B)/P_(R)-series auxiliary-information-datadecrypting-extracting unit 71 performs the decryption by using the keydata DKCA for the encrypted P_(B)/P_(R)-series auxiliary informationdata DCAE included in the encrypted P_(B)/P_(R)-series auxiliary datapacket PCAE in accordance with the timing control signal Tk toselectively enter a state in which the P_(B)/P_(R)-series auxiliaryinformation data DCA, which is based on the encrypted P_(B)/P_(R)-seriesauxiliary information data DCAE and which includes no inhibited codes,is reproduced or a state in which P_(B)/P_(R)-series auxiliaryinformation data DCA is extracted from the P_(B)/P_(R)-series auxiliarydata packet PCA.

As a result, the Y-series video data DYV is output from the Y-seriesvideo-data decrypting unit 68, the P_(B)/P_(R)-series video data DCV isoutput from the P_(B)/P_(R)-series video-data decrypting unit 69, theY-series auxiliary information data DYA is output from the Y-seriesauxiliary-information-data decrypting-extracting unit 70, and theP_(B)/P_(R)-series auxiliary information data DCA is output from theP_(B)/P_(R)-series auxiliary-information-data decrypting-extracting unit71. The Y-series video data DYV output from the Y-series video-datadecrypting unit 68 is supplied to a data recording unit 75, and thesupplied Y-series video data DYV is recorded in the data recording unit75 and is transmitted through an output I/F 76. The P_(B)/P_(R)-seriesvideo data DCV output from the P_(B)/P_(R)-series video-data decryptingunit 69 is supplied to the data recording unit 75, and the suppliedP_(B)/P_(R)-series video data DCV is recorded in the data recording unit75 and is transmitted through an output I/F 77. The Y-series auxiliaryinformation data DYA output from the Y-series auxiliary-information-datadecrypting-extracting unit 70 is supplied to the data recording unit 75,and the supplied Y-series auxiliary information data DYA is recorded inthe data recording unit 75 and is transmitted through an output I/F 78.The P_(B)/P_(R)-series auxiliary information data DCA output from theP_(B)/P_(R)-series auxiliary-information-data decrypting-extracting unit71 is supplied to the data recording unit 75, and the suppliedP_(B)/P_(R)-series auxiliary information data DCA is stored in the datarecording unit 75 and is transmitted through an output I/F 79.

FIG. 13 shows an example of the structure of the Y-seriesauxiliary-information-data decrypting-extracting unit 70. In the exampleof the structure shown in FIG. 13, the encrypted Y-series auxiliary datapacket PYAE or the Y-series auxiliary data packet PYA is supplied to adecryption processor 81, a delay device 82, and a packet-code-datadetector 83. The key data DKYA is supplied to a key data converter 84.The timing control signal Tj is supplied to a control signal generator85 that transmits control signals TG, TH, and YI having differentfunctions in accordance with the timing control signal Tj or inaccordance with other setting conditions.

The control signal TG is supplied from the control signal generator 85to the key data converter 84. The key data converter 84 transmits pseudorandom number data DYYA formed based on the key data DKYA at a timingcorresponding to the control signal TG, and supplies the pseudo randomnumber data DYYA to the decryption processor 81.

When the encrypted Y-series auxiliary data packet PYAE is supplied tothe decryption processor 81, the delay device 82, and thepacket-code-data detector 83 in this structure, the following operationis carried out.

The decryption processor 81 performs the decryption by using the pseudorandom number data DYYA supplied from the key data converter 84 for theencrypted Y-series auxiliary information data DYAE included in theencrypted Y-series auxiliary data packet PYAE to reproduce the Y-seriesauxiliary information data DYA, which is based on the encrypted Y-seriesauxiliary information data DYAE and which includes no inhibited codes,and supplies the Y-series auxiliary information data DYA to a dataselector 86.

The delay device 82 delays the encrypted Y-series auxiliary informationdata DYAE included in the encrypted Y-series auxiliary data packet PYAE,and supplies the delayed encrypted Y-series auxiliary information dataDYAE to the data selector 86.

The packet-code-data detector 83 detects the EADF, which is included inthe encrypted Y-series auxiliary data packet PYAE and with which theoriginal ADF is replaced, or the EDID with which the original DID isreplaced. Whether the EADF or the EDID is detected is set in advance.

The control signals TH and TI are supplied from the control signalgenerator 85 to the packet-code-data detector 83. The control signal THindicates a timing of the ADF or DID in the Y-series auxiliary datapacket. Whether the control signal TH indicates a timing of the ADF or atiming of the DID is determined in accordance with whether thepacket-code-data detector 83 is set so as to detect the EADF or is setso as to detect the EDID. The control signal TI indicates that the EADFwith which the original ADF is replaced is to be detected or that theEDID with which the original DID is replaced is to be detected. Whetherthe control signal TI indicates the detection of the EADF or thedetection of the EDID is determined in accordance with whether thepacket-code-data detector 83 is set so as to detect the EADF or is setso as to detect the EDID.

The packet-code-data detector 83 detects the EADF or EDID included inthe encrypted Y-series auxiliary data packet PYAE in accordance with theindication in the control signal TI at the timing specified by thecontrol signal TH, transmits a detection output signal SW correspondingto the detection of the EADF or EDID, and supplies the detection outputsignal SW to the data selector 86. The packet-code-data detector 83 alsotransmits a data available period flag ETF representing a period duringwhich the encrypted Y-series auxiliary information data DYAE isavailable, based on code data other than the EADF or EDID, included inthe encrypted Y-series auxiliary data packet PYAE.

The data selector 86, to which the detection output signal SW issupplied from the packet-code-data detector 83, extracts the Y-seriesauxiliary information data DYA from the decryption processor 81 inresponse to the detection output signal SW, and outputs the Y-seriesauxiliary information data DYA.

When the Y-series auxiliary data packet PYA is supplied to thedecryption processor 81, the delay device 82, and the packet-code-datadetector 83, the following operation is carried out.

The decryption processor 81 performs the decryption by using the pseudorandom number data DYYA supplied from the key data converter 84 for theY-series auxiliary information data DYA included in Y-series auxiliarydata packet PYA. However, no meaningful data is reproduced in this case.

The delay device 82 delays the Y-series auxiliary information data DYAincluded in the Y-series auxiliary data packet PYA, and supplies thedelayed Y-series auxiliary information data DYA to the data selector 86.

The packet-code-data detector 83 detects the ADF or DID included inY-series auxiliary data packet PYA Whether the ADF or the DID isdetected is set in advance.

The control signals TH and TI are supplied from the control signalgenerator 85 to the packet-code-data detector 83. The control signal THindicates a timing of the ADF or DID in the Y-series auxiliary datapacket. Whether the control signal TH indicates a timing of the ADF or atiming of the DID is determined in accordance with whether thepacket-code-data detector 83 is set so as to detect the ADF or is set soas to detect the DID. The control signal TI indicates that the ADF is tobe detected or that the DID is to be detected. Whether the controlsignal TI indicates the detection of the ADF or the detection of the DIDis determined in accordance with whether the packet-code-data detector83 is set so as to detect the ADF or is set so as to detect the DID.

The packet-code-data detector 83 detects the ADF or DID included in theY-series auxiliary data packet PYA in accordance with the indication inthe control signal TI at the timing specified by the control signal TH,transmits the detection output signal SW corresponding to the detectionof the ADF or DID, and supplies the detection output signal SW to thedata selector 86. The packet-code-data detector 83 also transmits thedata available period flag ETF representing a period during which theY-series auxiliary information data DYA is available, based on code dataother than the ADF or DID, included in the Y-series auxiliary datapacket PYA.

The data selector 86, to which the detection output signal SW issupplied from the packet-code-data detector 83, extracts the Y-seriesauxiliary information data DYA from the delay device 82 in response tothe detection output signal SW, and outputs the Y-series auxiliaryinformation data DYA.

The Y-series auxiliary information data DYA is output from the dataselector 86 in the manner described above.

In the example of the structure shown in FIG. 13, the decryptionprocessor 81 may include, for example, a bit-wise exclusive OR circuitwhen the encrypted Y-series auxiliary information data DYAE included inthe encrypted Y-series auxiliary data packet PYAE is encrypted digitalaudio information data or the Y-series auxiliary information data DYAincluded in the Y-series auxiliary data packet PYA is digital audioinformation data.

An example of the structure of the PP_(B)/P_(R)-seriesauxiliary-information-data decrypting-extracting unit 71 is similar tothe example of the structure of the Y-series auxiliary-information-datadecrypting-extracting unit 70 shown in FIG. 13. In the example of thestructure of the P_(B)/P_(R)-series auxiliary-information-datadecrypting-extracting unit 71, the P_(B)/P_(R)-series auxiliaryinformation data DCA is output from a data selector corresponding to thedata selector 86 in FIG. 13.

FIG. 14 shows another example of the structure of the Y-seriesauxiliary-information-data decrypting-extracting unit 70. The exampleshown in FIG. 14 has many components similar to those in the exampleshown in FIG. 13, and the same reference numerals are used in FIG. 14 toidentify the same components and data shown in FIG. 13. A duplicateddescription of such components and data is omitted herein.

In the example of the structure shown in FIG. 14, the encrypted Y-seriesauxiliary data packet PYAE or the Y-series auxiliary data packet PYA issupplied to a packet-code-data detector 91, an error corrector 92, and adelay device 93. Control signals TH and TI are also supplied from thecontrol signal generator 85 to the packet-code-data detector 91.

The packet-code-data detector 91 detects whether the encrypted Y-seriesauxiliary data packet PYAE or the Y-series auxiliary data packet PYA hasthe error correction data, for example, the error correction data DECEor DEC generated by the error-correction-data generator 39 in FIG. 9,inserted thereinto or the encrypted Y-series auxiliary data packet PYAEor the Y-series auxiliary data packet PYA has no error correction datainserted thereinto. When the encrypted Y-series auxiliary data packetPYAE or the Y-series auxiliary data packet PYA has the error correctiondata inserted thereinto, the packet-code-data detector 91 supplies anerror correction control signal SEC to the error corrector 92.

The error corrector 92 performs error correction by using the errorcorrection data inserted into the encrypted Y-series auxiliary-datapacket PYAE or the Y-series auxiliary data packet PYA for the encryptedY-series auxiliary information data DYAE or the Y-series auxiliaryinformation data DYA included in the encrypted Y-series auxiliary datapacket PYAE or the Y-series auxiliary data packet PYA having the errorcorrection data inserted thereinto in response to the error correctioncontrol signal SEC. The error correction in the error corrector 92 formsan encrypted Y-series auxiliary data packet PYAE′ or a Y-seriesauxiliary data packet PYA′ including the encrypted Y-series auxiliaryinformation data DYAE or the Y-series auxiliary information data DYAsubjected to the error correction, and the encrypted Y-series auxiliarydata packet PYAE′ or the Y-series auxiliary data packet PYA′ is suppliedto a data selector 94.

The delay device 93 delays the encrypted Y-series auxiliary data packetPYAE or the Y-series auxiliary data packet PYA by a time correspondingto the time required for the error correction of the encrypted Y-seriesauxiliary information data DYAE or the Y-series auxiliary informationdata DYA included in the encrypted Y-series auxiliary data packet PYAEor the Y-series auxiliary data packet PYA in the error corrector 92, andsupplies the delayed encrypted Y-series auxiliary data packet PYAE orY-series auxiliary data packet PYA to the data selector 94.

The packet-code-data detector 91 supplies, to the data selector 94, acontrol signal SWE indicating that the encrypted Y-series auxiliary datapacket PYAE or the Y-series auxiliary data packet PYA has the errorcorrection data inserted thereinto or that the encrypted Y-seriesauxiliary data packet PYAE or the Y-series auxiliary data packet PYA hasno error correction data inserted thereinto. When the control signal SWEindicates that the encrypted Y-series auxiliary data packet PYAE or theY-series auxiliary data packet PYA has the error correction datainserted thereinto, the data selector 94 extracts the encrypted Y-seriesauxiliary data packet PYAE′ or the Y-series auxiliary data packet PYA′supplied from the error corrector 92 and supplies the extractedencrypted Y-series auxiliary data packet PYAE′ or Y-series auxiliarydata packet PYA′ to a decryption processor 81 and a delay device 82.When the control signal SWE indicates that the encrypted Y-seriesauxiliary data packet PYAE or the Y-series auxiliary data packet PYA hasno error correction data inserted thereinto, the data selector 94extracts the encrypted Y-series auxiliary data packet PYAE or theY-series auxiliary data packet PYA supplied from the delay device 93 andsupplies the extracted encrypted Y-series auxiliary data packet PYAE orY-series auxiliary data packet PYA to the decryption processor 81 andthe delay device 82.

The decryption processor 81 and the delay device 82 process theencrypted Y-series auxiliary data packet PYAE′ or the Y-series auxiliarydata packet PYA′, or the encrypted Y-series auxiliary data packet PYAEor the Y-series auxiliary data packet PYA in the same manner as in theprocessing of the encrypted Y-series auxiliary data packet PYAE or theY-series auxiliary data packet PYA by the decryption processor 81 andthe delay device 82 in FIG. 13.

The packet-code-data detector 91 outputs the detection output signal SWand the data available period flag ETF, like the packet-code-datadetector 83 in FIG. 13, and supplies the detection output signal SW to adata selector 86.

Other components and the operation in the example of the structure shownin FIG. 14 are similar to those in the example of the structure shown inFIG. 13. The Y-series auxiliary information data DYA is output from thedata selector 86.

Another example of the structure of the PP_(B)/P_(R)-seriesauxiliary-information-data decrypting-extracting unit 71 is similar tothe other example of the structure of the Y-seriesauxiliary-information-data decrypting-extracting unit 70 shown in FIG.14. In the other example of the structure of the P_(B)/P_(R)-seriesauxiliary-information-data decrypting-extracting unit 71, theP_(B)/P_(R)-series auxiliary information data DCA is output from a dataselector corresponding to the data selector 86 in FIG. 14.

Although the encrypted HD-SDI signal is transmitted in the aboveexamples of the data transmission apparatus and the encrypted HD-SDIsignal is received in the above examples of the data receptionapparatus, the data transmission method and the data transmissionapparatus according to the invention described in the claims of thisapplication is not limitedly used in the transmission of the encryptedHD-SDI signal and the data reception method and the data receptionapparatus according to the invention described in the claims of thisapplication are not limitedly used in the reception of the encryptedHD-SDI signal. The data transmission method and the data transmissionapparatus and the data reception method and the data receptionapparatus, according to the invention described in the claims of thisapplication, are applicable to the transmission and the reception of,for example, an encrypted high-definition-serial data transportinterface (HD-SDTI) signal and an encrypted Ethernet® signal.

INDUSTRIAL APPLICABILITY

As described above, in the data transmission method according to theinvention described in any of Claims 1 to 3 in the claims of thisapplication or the data transmission apparatus according to theinvention described in any of Claims 7 to 9 in the claims of thisapplication, the encrypted information data including no inhibited codesis generated and the encrypted data packet including the encryptedinformation data is transmitted. Accordingly, in the generation ofencrypted serial data based on the transmitted encrypted data packet,the encrypted serial data does not include a part in which undesiredinhibited codes are converted into serial data.

The first combination of the plurality of inhibited codes forming thedata flag included in the encrypted data packet is replaced with thesecond combination of the inhibited codes, different from the firstcombination. Accordingly, when the receiving apparatus receiving thetransmitted encrypted data packet does not include decrypting means forthe encrypted information data included in the encrypted data packet,the data flag is not detected and, therefore, the encrypted data packetis not received, so that reproduction of information data based on theencrypted information data included in the encrypted data packet is notperformed. Consequently, when the receiving apparatus receiving theencrypted data packet has a speaker, serving as audio reproducing meansfor reproducing audio based on the reproduced digital audio information,but does not have the decrypting means for the encrypted informationdata included in the encrypted data packet, an undesirable audio signalformed based on the encrypted information data is not supplied to thespeaker. As a result, a situation in which an excessive current based onthe undesired audio signal is applied to the speaker to damage thespeaker can be avoided.

In the data transmission method according to the invention described inClaim 2 or the data transmission apparatus according to the inventiondescribed in Claim 8, the error correction data for the encryptedinformation data is generated along with the encrypted information dataand the encrypted information data and the error correction datacorresponding to the encrypted information data are included in theencrypted data packet. Accordingly, a situation in which the encryptioncauses a reduction in performance of the error correction of theencrypted information data can be avoided.

In the data transmission method according to the invention described inClaim 3 or the data transmission apparatus according to the inventiondescribed in Claim 9, the data packet is included in each of the datasequences and the encrypted data packet based on the data packet isformed for every data sequence. Accordingly, even when a streamconverter using an FIFO memory is used in the encryption in order toform an encrypted auxiliary data packet, a situation in which thewriting period for the FIFO memory is not sufficiently provided to emptythe FIFO memory does not arise. Consequently, a reduction in quality ofthe encryption security of the encrypted auxiliary data packet is notcaused.

With the data transmission method according to the invention describedin any of Claims 1 to 3 in the claims of this application or the datatransmission apparatus according to the invention described in any ofClaims 7 to 9 in the claims of this application, when the encrypted HDsignal including the encrypted auxiliary data packet is formed and theencrypted HD-SDI signal based on the encrypted HD signal is transmitted,it is possible to selectively perform the encryption for every auxiliarydata packet in each line of the Y data sequence and the P_(B)/P_(R) datasequence forming the HD signal, thus improving the flexibility in theactual use.

Similarly, in the data transmission method according to the inventiondescribed in any of Claims 4 to 6 in the claims of this application orthe data transmission apparatus according to the invention described inany of Claims 10 to 12 in the claims of this application, the encryptedinformation data including no inhibited codes is generated and theencrypted data packet including the encrypted information data istransmitted. Accordingly, in the generation of encrypted serial databased on the transmitted encrypted data packet, the encrypted serialdata does not include a part in which undesired inhibited codes areconverted into serial data.

The first code in the identification data representing a type of theencrypted information data is replaced with the second code that isother than the inhibited codes and that is different from the firstcode. Accordingly, when the receiving apparatus receiving thetransmitted encrypted data packet does not include decrypting means forthe encrypted information data included in the encrypted data packet,the type of the original information data represented by theidentification data before the replacement is not recognized and,therefore, the data provided as the reproduced information data based onthe encrypted information data included in the encrypted data packet isnot processed as data belonging to the type of the original informationdata represented by the identification data before the replacement.Consequently, for example, when the receiving apparatus receiving theencrypted data packet has a speaker, serving as audio reproducing meansfor reproducing audio based on the reproduced digital audio information,but does not have the decrypting means for the encrypted informationdata included in the encrypted data packet, no signal based on theencrypted information data is supplied to the speaker and, therefore, anundesirable audio signal generated based on the encrypted informationdata is not supplied to the speaker. As a result, a situation in whichan excessive current based on the undesired audio signal is applied tothe speaker to damage the speaker can be avoided.

With the data transmission method according to the invention describedin any of Claims 4 to 6 in the claims of this application or the datatransmission apparatus according to the invention described in any ofClaims 10 to 12 in the claims of this application, when the encrypted HDsignal including the encrypted auxiliary data packet is formed and theencrypted HD-SDI signal based on the encrypted HD signal is transmitted,it is possible to selectively perform the encryption for every auxiliarydata packet in each line of the Y data sequence and the P_(B)/P_(R) datasequence forming the HD signal, thus improving the flexibility in theactual use.

In the data transmission method according to the invention described inany of Claims 1 to 6 in the claims of this application or the datatransmission apparatus according to the invention described in any ofClaims 7 to 12 in the claims of this application, it is possible to formthe encrypted auxiliary data packet by the encryption of the auxiliarydata packet formed of the auxiliary data included in the HD signalforming the HD-SDI signal, to generate the encrypted HD signal includingthe encrypted auxiliary data packet, and to transmit the encryptedHD-SDI signal based on the encrypted HD signal while selectivelyperforming the encryption for every auxiliary data packet and avoidingthe disadvantages involved in the application of proposed technologiesdescribed above.

In the data reception method according to the invention described in anyof Claims 13 to 15 in the claims of this application or the datareception apparatus according to the invention described in any ofClaims 19 to 21 in the claims of this application, the encrypted datapacket that is transmitted, that includes the encrypted information dataincluding no inhibited codes, and that has the data flag formed of thesecond combination of a plurality of inhibited codes, with which secondcombination of the inhibited codes the first combination of theinhibited codes is replaced, the second combination being different fromthe first combination, is received; the decryption is performed for theencrypted information data included in the encrypted data packet togenerate the reproduced information data; the data flag included in theencrypted data packet is detected; and the reproduced information datais extracted in accordance with the detection output resulting from thedetection.

In the above process, the encrypted information data included in theencrypted data packet includes no inhibited codes. Accordingly, in thegeneration of encrypted serial data based on the transmitted encrypteddata packet, the encrypted serial data does not include a part in whichundesired inhibited codes are converted into serial data. Consequently,the reception of the encrypted data packet that is transmitted and thatincludes the encrypted information data including no inhibited codesdoes not have the disadvantage in that undesired inhibited codes aredetected and, therefore, the encrypted data packet is not received.

In addition, the decryption is performed for the encrypted informationdata including no inhibited codes, in the received encrypted datapacket, to generate the reproduced information data. The data flagformed of the first combination of the inhibited codes is replaced withthe second combination of the inhibited codes, the second combinationbeing different from the first combination, is detected and a timingwhen the reproduced information data is generated is detected based onthe detection output representing the reception of the encrypted datapacket. At a timing detected based on the detection output representingthe reception of the encrypted data packet, the reproduced informationdata resulting from the decryption performed for the encryptedinformation data is extracted. Accordingly, appropriate reproducedinformation data can be reproduced.

In the data reception method according to the invention described in anyof Claims 16 to 18 in the claims of this application or the datareception apparatus according to the invention described in any ofClaims 22 to 24 in the claims of this application, the encrypted datapacket that is transmitted, that has the data flag formed of theinhibited codes, and that includes the encrypted information dataincluding no inhibited codes, the data flag being followed by theidentification data that has the second code other than the inhibitedcodes, with which second code the first code is replaced, the secondcode being different from the first code, is received; the decryption isperformed for the encrypted information data included in the encrypteddata packet to generate the reproduced information data; theidentification data included in the encrypted data packet is detected;and the reproduced information data is extracted in accordance with thedetection output resulting from the detection.

In the above process, the encrypted information data included in theencrypted data packet includes no inhibited codes. Accordingly, in thegeneration of encrypted serial data based on the transmitted encrypteddata packet, the encrypted serial data does not include a part in whichundesired inhibited codes are converted into serial data. Consequently,the reception of the encrypted data packet that is transmitted and thatincludes the encrypted information data including no inhibited codesdoes not have the disadvantage in that undesired inhibited codes aredetected and, therefore, the encrypted data packet is not received.

In addition, the decryption is performed for the encrypted informationdata including no inhibited codes, in the received encrypted datapacket, to generate the reproduced information data. The identificationdata having the second code other than the inhibited codes, differentfrom the original first code, with which second code the first code isreplaced, is detected and a timing when the reproduced information datais generated is detected based on the detection output representing thetiming corresponding to the position of the identification data in theencrypted data packet. At the detected timing, the reproducedinformation data resulting from the decryption performed for theencrypted information data is extracted. Accordingly, appropriatereproduced information data can be reproduced.

1. A data transmission method comprising the steps of: performingencryption for information data included in a data packet having a dataflag formed of a first combination of a plurality of inhibited codesthat are not used as information codes representing information, theinformation data being formed without using the inhibited codes, so asnot to generate the inhibited codes in order to generate encryptedinformation data that includes no inhibited codes; replacing the firstcombination of the plurality of inhibited codes in the data flag in thedata packet with a second combination of the inhibited codes, the secondcombination being different from the first combination, to form anencrypted data packet that has the replaced data flag and that includesthe encrypted information data; and transmitting the encrypted datapacket, wherein when the transmitted encrypted data packet does notinclude decrypting information, a type of original information datarepresented by identification data before the replacing is notrecognized and reproduced information data based on encryptedinformation data included in the encrypted data packet is not processedas data belonging to a same type of information as the information datarepresented by identification data before the replacement of the firstcombination with the second combination.
 2. The data transmission methodaccording to claim 1, wherein error correction data for the encryptedinformation data is generated along with the encrypted information data,and wherein the error correction data is incorporated in the encrypteddata packet.
 3. The data transmission method according to claim 1,wherein the data packet is included in each of a plurality of datasequences, and wherein the encrypted data packet based on the datapacket is formed for every data sequence.
 4. A data transmission methodcomprising the steps of: performing encryption for information dataincluded in a data packet having a data flag formed of a predeterminedcombination of a plurality of inhibited codes that are not used asinformation codes representing information, the information data beingformed without using the inhibited codes, the data flag being followedby identification data that includes a first code other than theinhibited codes to represent a type of the information data, so as notto generate the inhibited codes in order to generate encryptedinformation data that includes no inhibited codes; replacing the firstcode included in the identification data in the data packet with asecond code that is different from the first code and that is other thanthe inhibited codes to form an encrypted data packet that has the dataflag followed by the replaced identification data and that includes theencrypted information data; and transmitting the encrypted data packet,wherein when the transmitted encrypted data packet does not includedecrypting information, a type of original information data representedby identification data before the replacing is not recognized andreproduced information data based on encrypted information data includedin the encrypted data packet is not processed as data belonging to asame type of information as the information data represented byidentification data before the replacement of the first combination withthe second combination.
 5. The data transmission method according toclaim 4, wherein error correction data for the encrypted informationdata is generated along with the encrypted information data, and whereinthe error correction data is incorporated in the encrypted data packet.6. The data transmission method according to claim 4, wherein the datapacket is included in each of a plurality of data sequences, and whereinthe encrypted data packet based on the data packet is formed for everydata sequence.
 7. A data transmission apparatus comprising: anencryption processing unit configured to perform encryption forinformation data included in a data packet having a data flag formed ofa first combination of a plurality of inhibited codes that are not usedas information codes representing information, the information databeing formed without using the inhibited codes, so as not to generatethe inhibited codes in order to generate encrypted information data thatincludes no inhibited codes; an encrypted-data-packet forming unitconfigured to replace the first combination of the plurality ofinhibited codes in the data flag in the data packet with a secondcombination of the inhibited codes, the second combination beingdifferent from the first combination, to form an encrypted data packetthat has the replaced data flag and that includes the encryptedinformation data generated by the encryption processing unit; and a datatransmitting unit configured to transmit the encrypted data packetformed by the encrypted-data-packet forming unit, wherein when thetransmitted encrypted data packet does not include decryptinginformation, a type of original information data represented byidentification data before the replacing is not recognized andreproduced information data based on encrypted information data includedin the encrypted data packet is not processed as data belonging to asame type of information as the information data represented byidentification data before the replacement of the first combination withthe second combination.
 8. The data transmission apparatus according toclaim 7, wherein the encryption processing unit generates errorcorrection data for the encrypted information data along with thegeneration of the encrypted information data, and wherein theencrypted-data-packet forming unit incorporates the error correctiondata generated by the encryption processing unit in the encrypted datapacket.
 9. The data transmission apparatus according to claim 7, whereinthe data packet is included in each of a plurality of data sequences,and wherein a plurality of combinations of the encryption processingunit and the encrypted-data-packet forming unit is providedcorresponding to the plurality of data sequences.
 10. A datatransmission apparatus comprising: an encryption processing unitconfigured to perform encryption for information data included in a datapacket having a data flag formed of a predetermined combination of aplurality of inhibited codes that are not used as information codesrepresenting information, the information data being formed withoutusing the reserved codes, the data flag being followed by identificationdata that includes a first code other than the reserved codes torepresent a type of the information data, so as not to generate theinhibited codes in order to generate encrypted information data thatdoes not use the inhibited codes; an encrypted-data-packet forming unitconfigured to replace the first code included in the identification datain the data packet with a second code that is different from the firstcode and that is other than the reserved codes to form an encrypted datapacket that has the data flag followed by the replaced identificationdata and that includes the encrypted information data generated by theencryption processing unit; and a data transmitting unit configured totransmit the encrypted data packet formed by the encrypted-data-packetforming unit, wherein when the transmitted encrypted data packet doesnot include decrypting information, a type of original information datarepresented by identification data before the replacing is notrecognized and reproduced information data based on encryptedinformation data included in the encrypted data packet is not processedas data belonging to a same type of information as the information datarepresented by identification data before the replacement of the firstcombination with the second combination.
 11. The data transmissionapparatus according to claim 10, wherein the encryption processing unitgenerates error correction data for the encrypted information data alongwith the generation of the encrypted information data, and wherein theencrypted-data-packet forming unit incorporates the error correctiondata generated by the encryption processing unit in the encrypted datapacket.
 12. The data transmission apparatus according to claim 10,wherein the data packet is included in each of a plurality of datasequences, and wherein a plurality of combinations of the encryptionprocessing unit and the encrypted-data-packet forming unit is providedcorresponding to the plurality of data sequences.
 13. A data receptionmethod comprising the steps of: receiving encrypted data packet that istransmitted and that has a data flag formed of a second combination of aplurality of inhibited codes that are not used as information codesrepresenting information, with which second combination of the inhibitedcodes a first combination of the inhibited codes is replaced, the secondcombination being different from the first combination, the encrypteddata packet including encrypted information data that includes noreserved codes and that results from encryption performed forinformation data formed without using the inhibited codes so as not togenerate the inhibited codes; performing decryption for the encryptedinformation data included in the encrypted data packet to generatereproduced information data; detecting the data flag included in theencrypted data packet; and extracting the reproduced information data inaccordance with a detection output resulting from the detection, whereinwhen the received encrypted data packet does not include decryptinginformation, a type of original information data represented byidentification data before the replacing is not recognized andreproduced information data based on encrypted information data includedin the encrypted data packet is not processed as data belonging to asame type of information as the information data represented byidentification data before the replacement of the first combination withthe second combination.
 14. The data reception method according to claim13, wherein the encrypted data packet has the data flag and includeserror correction data for the encrypted information data along with theencrypted information data, and wherein the error correction dataincluded in the encrypted data packet is received to perform errorcorrection for the encrypted information data by using the errorcorrection data and the decryption is performed for the encryptedinformation data subjected to the error correction to generate thereproduced information data.
 15. The data reception method according toclaim 13, wherein the encrypted data packet is included in each of aplurality of data sequences, and wherein, for every data sequence, thedecryption is performed for the encrypted information data included inthe encrypted data packet, the data flag included in the encrypted datapacket is detected, and the reproduced information data is extracted.16. A data reception method comprising the steps of: receiving encrypteddata packet that is transmitted, that has a data flag formed of apredetermined combination of a plurality of inhibited codes that are notused as information codes representing information, and that includesencrypted information data resulting from encryption performed forinformation data formed without using the inhibited codes so as not togenerate the inhibited codes and including no reserved codes, the dataflag being followed by identification data that has a second code otherthan the inhibited codes, with which second code a first code that isother than the inhibited codes and that represents a type of theinformation data is replaced, the second code being different from thefirst code; performing decryption for the encrypted information dataincluded in the encrypted data packet to generate reproduced informationdata; detecting the identification data included in the encrypted datapacket; and extracting the reproduced information data in accordancewith a detection output resulting from the detection, wherein when thereceived encrypted data packet does not include decrypting information,a type of original information data represented by identification databefore the replacing is not recognized and reproduced information databased on encrypted information data included in the encrypted datapacket is not processed as data belonging to a same type of informationas the information data represented by identification data before thereplacement of the first combination with the second combination. 17.The data reception method according to claim 16, wherein the encrypteddata packet has the data flag followed by the identification data andincludes error correction data for the encrypted information data alongwith the encrypted information data, and wherein the error correctiondata included in the encrypted data packet is received to perform errorcorrection for the encrypted information data by using the errorcorrection data and the decryption is performed for the encryptedinformation data subjected to the error correction to generate thereproduced information data.
 18. The data reception method according toclaim 16, wherein the encrypted data packet is included in each of aplurality of data sequences, and wherein, for every data sequence, thedecryption is performed for the encrypted information data included inthe encrypted data packet, the identification data included in theencrypted data packet is detected, and the reproduced information dataextracted.
 19. A data reception apparatus comprising: a data-sequencereproducing unit configured to receive encrypted data packet that istransmitted and that has a data flag formed of a second combination of aplurality of inhibited codes that are not used as information codesrepresenting information, with which second combination of the inhibitedcodes a first combination of the inhibited codes is replaced, the secondcombination being different from the first combination, the encrypteddata packet including encrypted information data that includes noinhibited codes and that results from encryption performed forinformation data formed without using the inhibited codes so as not togenerate the inhibited codes; a decryption processing unit configured toperform decryption for the encrypted information data included in theencrypted data packet received by the data-sequence reproducing unit togenerate reproduced information data; a data detecting unit configuredto detect the data flag included in the encrypted data packet; and adata selecting unit configured to extract the reproduced informationdata generated by the decryption processing unit in accordance with adetection output supplied from the data detecting unit, wherein when thereceived encrypted data packet does not include decrypting information,a type of original information data represented by identification databefore the replacing is not recognized and reproduced information databased on encrypted information data included in the encrypted datapacket is not processed as data belonging to a same type of informationas the information data represented by identification data before thereplacement of the first combination with the second combination. 20.The data reception apparatus according to claim 19, wherein theencrypted data packet has the data flag and includes error correctiondata for the encrypted information data along with the encryptedinformation data, and wherein the decryption processing unit receivesthe error correction data included in the encrypted data packet toperform error correction for the encrypted information data by using theerror correction data and the decryption is performed for the encryptedinformation data subjected to the error correction to generate thereproduced information data.
 21. The data reception apparatus accordingto claim 19, wherein the encrypted data packet is included in each of aplurality of data sequences, and wherein a plurality of combinations ofthe decryption processing unit, the data detecting unit, and the dataselecting unit is provided corresponding to the plurality of datasequences.
 22. A data reception apparatus comprising: a data-sequencereproducing unit configured to receive encrypted data packet that istransmitted, that has a data flag formed of a predetermined combinationof a plurality of inhibited codes that are not used as information codesrepresenting information, and that includes encrypted information dataresulting from encryption performed for information data formed withoutusing the inhibited codes so as not to generate the inhibited codes andincluding no inhibited codes, the data flag being followed byidentification data that has a second code other than the inhibitedcodes, with which second code a first code that is other than theinhibited codes and that represents a type of the information data isreplaced, the second code being different from the first code; adecryption processing unit configured to perform decryption for theencrypted information data included in the encrypted data packetreceived by the data-sequence reproducing unit to generate reproducedinformation data; a data detecting unit configured to detect theidentification data included in the encrypted data packet; and a dataselecting unit configured to extract the reproduced information datagenerated by the decryption processing unit in accordance with adetection output supplied from the data detecting unit, wherein when thereceived encrypted data packet does not include decrypting information,a type of original information data represented by identification databefore the replacing is not recognized and reproduced information databased on encrypted information data included in the encrypted datapacket is not processed as data belonging to a same type of informationas the information data represented by identification data before thereplacement of the first combination with the second combination. 23.The data reception apparatus according to claim 22, wherein theencrypted data packet has the data flag followed by the identificationdata and includes error correction data for the encrypted informationdata along with the encrypted information data, and wherein thedecryption processing unit receives the error correction data includedin the encrypted data packet to perform error correction for theencrypted information data by using the error correction data and thedecryption is performed for the encrypted information data subjected tothe error correction to generate the reproduced information data. 24.The data reception apparatus according to claim 19, wherein theencrypted data packet is included in each of a plurality of datasequences, and wherein a plurality of combinations of the decryptionprocessing unit, the data detecting unit, and the data selecting unit isprovided corresponding to the plurality of data sequences.